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220 results on '"Delcey, Mickaël G."'

1. Perspective: Multi-configurational methods in bio-inorganic chemistry

Author

Jørgensen, Frederik K., Delcey, Mickaël G., and Hedegård, Erik D.

Subjects
Physics - Chemical Physics
Abstract

Transition metal ions play crucial roles in the structure and function of numerous proteins, contributing to essential biological processes such as catalysis, electron transfer, and oxygen binding. However, accurately modeling the electronic structure and properties of metalloproteins poses significant challenges due to the complex nature of their electronic configurations and strong correlation effects. Multiconfigurational quantum chemistry methods are, in principle, the most appropriate tools for addressing these challenges, offering the capability to capture the inherent multi-reference character and strong electron correlation present in bio-inorganic systems. Yet their computational cost has long hindered wider adoption, making methods such as Density Functional Theory (DFT) the method of choice. However, advancements over the past decade have substantially alleviated this limitation, rendering multiconfigurational quantum chemistry methods more accessible and applicable to a wider range of bio-inorganic systems. In this perspective, we discuss some of these developments and how they have already been used to answer some of the most important questions in bio-inorganic chemistry. We also comment on ongoing developments in the field and how the future of the field may evolve., Comment: Perspective, 13 pages, 4 figures, 2 tables

Published
2024

2. Tracing the 267 nm-Induced Radical Formation in Dimethyl Disulfide Using Time-Resolved X‑ray Absorption Spectroscopy

Author

Schnorr, Kirsten, Bhattacherjee, Aditi, Oosterbaan, Katherine J, Delcey, Mickaël G, Yang, Zheyue, Xue, Tian, Attar, Andrew R, Chatterley, Adam S, Head-Gordon, Martin, Leone, Stephen R, and Gessner, Oliver

Subjects
Physical Sciences, Chemical Sciences, Physical Chemistry, Chemical sciences, Physical sciences
Abstract

Disulfide bonds are pivotal for the structure, function, and stability of proteins, and understanding ultraviolet (UV)-induced S-S bond cleavage is highly relevant for elucidating the fundamental mechanisms underlying protein photochemistry. Here, the near-UV photodecomposition mechanisms in gas-phase dimethyl disulfide, a prototype system with a S-S bond, are probed by ultrafast transient X-ray absorption spectroscopy. The evolving electronic structure during and after the dissociation is simultaneously monitored at the sulfur L1,2,3-edges and the carbon K-edge with 100 fs (FWHM) temporal resolution using the broadband soft X-ray spectrum from a femtosecond high-order harmonics light source. Dissociation products are identified with the help of ADC and RASPT2 electronic-structure calculations. Rapid dissociation into two CH3S radicals within 120 ± 30 fs is identified as the major relaxation pathway after excitation with 267 nm radiation. Additionally, a 30 ± 10% contribution from asymmetric CH3S2 + CH3 dissociation is indicated by the appearance of CH3 radicals, which is, however, at least partly the result of multiphoton excitation.

Published
2019

6. The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

Author

Fundación la Caixa, European Commission, Ministerio de Ciencia e Innovación (España), Department of Energy (US), Swiss National Science Foundation, Ministero dell'Istruzione, dell'Università e della Ricerca, Carl Trygger Foundation, Royal Society (UK), Independent Research Fund Denmark, German Research Foundation, Generalitat de Catalunya, Olle Engkvist Foundation, National Centre for Research and Development (Poland), National Science Foundation (US), Academy of Finland, Knut and Alice Wallenberg Foundation, Swedish Research Council, Université de Nantes, Japan Society for the Promotion of Science, Università degli Studi di Siena, Novo Nordisk Foundation, Argonne National Laboratory (US), National University of Singapore, Air Force Office of Scientific Research (US), Linköping University, Centre National de la Recherche Scientifique (France), Li Manni, Giovanni [0000-0002-3666-3880], Fdez Galván, Ignacio [0000-0002-0684-7689], #NODATA#, Aleotti, Flavia [0000-0002-7176-5305], Aquilante, Francesco [0000-0003-4422-3938], Autschbach, Jochen [0000-0001-9392-877X], Avagliano, Davide [0000-0001-5539-9731], Baiardi, Alberto [0000-0001-9112-8664], Bao, Jie J. [0000-0003-0197-3405], Battaglia, Stefano [0000-0002-5082-2681], Blanco-González, Alejandro [0000-0001-7379-2588], Bokarev, Sergey I. [0000-0003-0779-5013], Broer, Ria [0000-0002-5437-9509], Cacciari, Roberto [0000-0001-8290-4297], Calio, Paul B. [0000-0001-8385-2628], Carlson, Rebecca K. [0000-0002-1710-5816], Carvalho Couto, Rafael [0000-0003-4020-0923], Cerdán, L. [0000-0002-7174-2453], Chibotaru, Liviu F. [0000-0003-1556-0812], Chilton, Nicholas F. [0000-0002-8604-0171], Church, Jonathan Richard [0000-0001-5986-1305], Conti, Irene [0000-0001-7982-4480], Coriani, Sonia [0000-0002-4487-897X], Cuéllar-Zuquin, Juliana [0000-0002-0127-579X], Daoud, Razan E. [0000-0001-7034-0770], Dattani, Nike [0000-0001-5667-3632], Decleva, Piero [0000-0002-7322-887X], de Graaf, Coen [0000-0001-8114-6658], Delcey, Mickaël G. [0000-0001-9883-3569], De Vico, Luca [0000-0002-2821-5711], Dobrautz, Werner [0000-0001-6479-1874], Dong, Sijia S. [0000-0001-8182-6522], Feng, Rulin [0000-0002-9812-3804], Ferré, Nicolas [0000-0002-5583-8834], Filatov Gulak, Michael [0000-0002-1541-739X], Gagliardi, Laura [0000-0001-5227-1396], Garavelli, Marco [0000-0002-0796-289X], González, Leticia [0000-0001-5112-794X], Guo, Meiyuan [0000-0003-2474-6264], Hennefarth, Matthew R. [0000-0002-6601-2253], Hermes, Matthew R. [0000-0001-7807-2950], Huix-Rotllant, Miquel [0000-0002-2131-7328], Jaiswal, Vishal Kumar [0000-0002-5090-7984], Kaliakin, Danil S. [0000-0002-9354-8248], King, Daniel S. [0000-0003-0208-5274], Larsson, Ernst D. [0000-0001-7655-2993], Lehtola, Susi [0000-0001-6296-8103], Lepetit, Marie-Bernadette [0000-0001-8730-4282], Lischka, Hans [0000-0002-5656-3975], Lundberg, Marcus [0000-0002-1312-1202], Mai, Sebastian [0000-0001-5327-8880], Marquetand, Philipp [0000-0002-8711-1533], Merritt, Isabella C. D. [0000-0002-7965-7798], Nenov, Artur [0000-0003-3071-5341], Nguyen, Vu Ha Anh [0000-0002-4177-0656], Nishimoto, Yoshio [0000-0001-5581-4712], Oakley, Meagan S. [0000-0001-5072-7572], Olivucci, Massimo [0000-0002-8247-209X], Oppel, Markus [0000-0001-6363-2310], Padula, Daniele [0000-0002-7171-7928], Pandharkar, Riddhish [0000-0003-4086-4308], Phung, Quan Manh [0000-0001-8205-5328], Plasser, Felix [0000-0003-0751-148X], Reiher, Markus [0000-0002-9508-1565], Rivalta, Ivan [0000-0002-1208-602X], Roca-Sanjuán, Daniel [0000-0001-6495-2770], Romig, Thies [0000-0002-9424-2398], Safari, Arta Anushirwan [0000-0003-4511-8902], Sánchez-Mansilla, Aitor [0000-0002-2601-190X], Sand, Andrew M. [0000-0002-7166-2066], Schapiro, Igor [0000-0001-8536-6869], Scott, Thais R. [0000-0002-5746-5517], Segarra-Martí, Javier [0000-0002-2076-3406], Segatta, Francesco [0000-0003-4150-6676], Sergentu, Dumitru-Claudiu [0000-0001-6570-5245], Shepard, Ron [0000-0002-0272-0824], Shu, Yinan [0000-0002-8371-0221], Sørensen, Lasse Kragh [0000-0002-1931-1867], Tenorio, Bruno Nunes Cabral [0000-0002-9702-998X], Truhlar, Donald G. [0000-0002-7742-7294], Ungur, Liviu [0000-0001-5015-4225], Vacher, Morgane [0000-0001-9418-6579], Veryazov, Valera [0000-0002-0172-7047], Li Manni, Giovanni, Fdez Galván, Ignacio, Alavi, Ali, Aleotti, Flavia, Aquilante, Francesco, Autschbach, Jochen, Avagliano, Davide, Baiardi, Alberto, Bao, Jie J., Battaglia, Stefano, Birnoschi, Letitia, Blanco-González, Alejandro, Bokarev, Sergey I., Broer, Ria, Cacciari, Roberto, Calio, Paul B., Carlson, Rebecca K., Carvalho Couto, Rafael, Cerdán, L., Chibotaru, Liviu F., Chilton, Nicholas F., Church, Jonathan Richard, Conti, Irene, Coriani, Sonia, Cuéllar-Zuquin, Juliana, Daoud, Razan E., Dattani, Nike, Decleva, Piero, de Graaf, Coen, Delcey, Mickaël G., De Vico, Luca, Dobrautz, Werner, Dong, Sijia S., Feng, Rulin, Ferré, Nicolas, Filatov Gulak, Michael, Gagliardi, Laura, Garavelli, Marco, González, Leticia, Guan, Yafu, Guo, Meiyuan, Hennefarth, Matthew R., Hermes, Matthew R., Hoyer, Chad E., Huix-Rotllant, Miquel, Jaiswal, Vishal Kumar, Kaiser, Andy, Kaliakin, Danil S., Khamesian, Marjan, King, Daniel S., Kochetov, Vladislav, Krośnicki, Marek, Kumaar, Arpit Arun, Larsson, Ernst D., Lehtola, Susi, Lepetit, Marie-Bernadette, Lischka, Hans, López Ríos, Pablo, Lundberg, Marcus, Ma, Dongxia, Mai, Sebastian, Marquetand, Philipp, Merritt, Isabella C. D., Montorsi, Francesco, Mörchen, Maximilian, Nenov, Artur, Nguyen, Vu Ha Anh, Nishimoto, Yoshio, Oakley, Meagan S., Olivucci, Massimo, Oppel, Markus, Padula, Daniele, Pandharkar, Riddhish, Phung, Quan Manh, Plasser, Felix, Raggi, Gerardo, Rebolini, Elisa, Reiher, Markus, Rivalta, Ivan, Roca-Sanjuán, Daniel, Romig, Thies, Safari, Arta Anushirwan, Sánchez-Mansilla, Aitor, Sand, Andrew M., Schapiro, Igor, Scott, Thais R., Segarra-Martí, Javier, Segatta, Francesco, Sergentu, Dumitru-Claudiu, Sharma, Prachi, Shepard, Ron, Shu, Yinan, Staab, Jakob K., Straatsma, Tjerk P., Sørensen, Lasse Kragh, Tenorio, Bruno Nunes Cabral, Truhlar, Donald G., Ungur, Liviu, Vacher, Morgane, Veryazov, Valera, Voß, Torben Arne, Weser, Oskar, Wu, Dihua, Yang, Xuchun, Yarkony, David, Zhou, Chen, Zobel, J Patrick, Lindh, Roland, Fundación la Caixa, European Commission, Ministerio de Ciencia e Innovación (España), Department of Energy (US), Swiss National Science Foundation, Ministero dell'Istruzione, dell'Università e della Ricerca, Carl Trygger Foundation, Royal Society (UK), Independent Research Fund Denmark, German Research Foundation, Generalitat de Catalunya, Olle Engkvist Foundation, National Centre for Research and Development (Poland), National Science Foundation (US), Academy of Finland, Knut and Alice Wallenberg Foundation, Swedish Research Council, Université de Nantes, Japan Society for the Promotion of Science, Università degli Studi di Siena, Novo Nordisk Foundation, Argonne National Laboratory (US), National University of Singapore, Air Force Office of Scientific Research (US), Linköping University, Centre National de la Recherche Scientifique (France), Li Manni, Giovanni [0000-0002-3666-3880], Fdez Galván, Ignacio [0000-0002-0684-7689], #NODATA#, Aleotti, Flavia [0000-0002-7176-5305], Aquilante, Francesco [0000-0003-4422-3938], Autschbach, Jochen [0000-0001-9392-877X], Avagliano, Davide [0000-0001-5539-9731], Baiardi, Alberto [0000-0001-9112-8664], Bao, Jie J. [0000-0003-0197-3405], Battaglia, Stefano [0000-0002-5082-2681], Blanco-González, Alejandro [0000-0001-7379-2588], Bokarev, Sergey I. [0000-0003-0779-5013], Broer, Ria [0000-0002-5437-9509], Cacciari, Roberto [0000-0001-8290-4297], Calio, Paul B. [0000-0001-8385-2628], Carlson, Rebecca K. [0000-0002-1710-5816], Carvalho Couto, Rafael [0000-0003-4020-0923], Cerdán, L. [0000-0002-7174-2453], Chibotaru, Liviu F. [0000-0003-1556-0812], Chilton, Nicholas F. [0000-0002-8604-0171], Church, Jonathan Richard [0000-0001-5986-1305], Conti, Irene [0000-0001-7982-4480], Coriani, Sonia [0000-0002-4487-897X], Cuéllar-Zuquin, Juliana [0000-0002-0127-579X], Daoud, Razan E. [0000-0001-7034-0770], Dattani, Nike [0000-0001-5667-3632], Decleva, Piero [0000-0002-7322-887X], de Graaf, Coen [0000-0001-8114-6658], Delcey, Mickaël G. [0000-0001-9883-3569], De Vico, Luca [0000-0002-2821-5711], Dobrautz, Werner [0000-0001-6479-1874], Dong, Sijia S. [0000-0001-8182-6522], Feng, Rulin [0000-0002-9812-3804], Ferré, Nicolas [0000-0002-5583-8834], Filatov Gulak, Michael [0000-0002-1541-739X], Gagliardi, Laura [0000-0001-5227-1396], Garavelli, Marco [0000-0002-0796-289X], González, Leticia [0000-0001-5112-794X], Guo, Meiyuan [0000-0003-2474-6264], Hennefarth, Matthew R. [0000-0002-6601-2253], Hermes, Matthew R. [0000-0001-7807-2950], Huix-Rotllant, Miquel [0000-0002-2131-7328], Jaiswal, Vishal Kumar [0000-0002-5090-7984], Kaliakin, Danil S. [0000-0002-9354-8248], King, Daniel S. [0000-0003-0208-5274], Larsson, Ernst D. [0000-0001-7655-2993], Lehtola, Susi [0000-0001-6296-8103], Lepetit, Marie-Bernadette [0000-0001-8730-4282], Lischka, Hans [0000-0002-5656-3975], Lundberg, Marcus [0000-0002-1312-1202], Mai, Sebastian [0000-0001-5327-8880], Marquetand, Philipp [0000-0002-8711-1533], Merritt, Isabella C. D. [0000-0002-7965-7798], Nenov, Artur [0000-0003-3071-5341], Nguyen, Vu Ha Anh [0000-0002-4177-0656], Nishimoto, Yoshio [0000-0001-5581-4712], Oakley, Meagan S. [0000-0001-5072-7572], Olivucci, Massimo [0000-0002-8247-209X], Oppel, Markus [0000-0001-6363-2310], Padula, Daniele [0000-0002-7171-7928], Pandharkar, Riddhish [0000-0003-4086-4308], Phung, Quan Manh [0000-0001-8205-5328], Plasser, Felix [0000-0003-0751-148X], Reiher, Markus [0000-0002-9508-1565], Rivalta, Ivan [0000-0002-1208-602X], Roca-Sanjuán, Daniel [0000-0001-6495-2770], Romig, Thies [0000-0002-9424-2398], Safari, Arta Anushirwan [0000-0003-4511-8902], Sánchez-Mansilla, Aitor [0000-0002-2601-190X], Sand, Andrew M. [0000-0002-7166-2066], Schapiro, Igor [0000-0001-8536-6869], Scott, Thais R. [0000-0002-5746-5517], Segarra-Martí, Javier [0000-0002-2076-3406], Segatta, Francesco [0000-0003-4150-6676], Sergentu, Dumitru-Claudiu [0000-0001-6570-5245], Shepard, Ron [0000-0002-0272-0824], Shu, Yinan [0000-0002-8371-0221], Sørensen, Lasse Kragh [0000-0002-1931-1867], Tenorio, Bruno Nunes Cabral [0000-0002-9702-998X], Truhlar, Donald G. [0000-0002-7742-7294], Ungur, Liviu [0000-0001-5015-4225], Vacher, Morgane [0000-0001-9418-6579], Veryazov, Valera [0000-0002-0172-7047], Li Manni, Giovanni, Fdez Galván, Ignacio, Alavi, Ali, Aleotti, Flavia, Aquilante, Francesco, Autschbach, Jochen, Avagliano, Davide, Baiardi, Alberto, Bao, Jie J., Battaglia, Stefano, Birnoschi, Letitia, Blanco-González, Alejandro, Bokarev, Sergey I., Broer, Ria, Cacciari, Roberto, Calio, Paul B., Carlson, Rebecca K., Carvalho Couto, Rafael, Cerdán, L., Chibotaru, Liviu F., Chilton, Nicholas F., Church, Jonathan Richard, Conti, Irene, Coriani, Sonia, Cuéllar-Zuquin, Juliana, Daoud, Razan E., Dattani, Nike, Decleva, Piero, de Graaf, Coen, Delcey, Mickaël G., De Vico, Luca, Dobrautz, Werner, Dong, Sijia S., Feng, Rulin, Ferré, Nicolas, Filatov Gulak, Michael, Gagliardi, Laura, Garavelli, Marco, González, Leticia, Guan, Yafu, Guo, Meiyuan, Hennefarth, Matthew R., Hermes, Matthew R., Hoyer, Chad E., Huix-Rotllant, Miquel, Jaiswal, Vishal Kumar, Kaiser, Andy, Kaliakin, Danil S., Khamesian, Marjan, King, Daniel S., Kochetov, Vladislav, Krośnicki, Marek, Kumaar, Arpit Arun, Larsson, Ernst D., Lehtola, Susi, Lepetit, Marie-Bernadette, Lischka, Hans, López Ríos, Pablo, Lundberg, Marcus, Ma, Dongxia, Mai, Sebastian, Marquetand, Philipp, Merritt, Isabella C. D., Montorsi, Francesco, Mörchen, Maximilian, Nenov, Artur, Nguyen, Vu Ha Anh, Nishimoto, Yoshio, Oakley, Meagan S., Olivucci, Massimo, Oppel, Markus, Padula, Daniele, Pandharkar, Riddhish, Phung, Quan Manh, Plasser, Felix, Raggi, Gerardo, Rebolini, Elisa, Reiher, Markus, Rivalta, Ivan, Roca-Sanjuán, Daniel, Romig, Thies, Safari, Arta Anushirwan, Sánchez-Mansilla, Aitor, Sand, Andrew M., Schapiro, Igor, Scott, Thais R., Segarra-Martí, Javier, Segatta, Francesco, Sergentu, Dumitru-Claudiu, Sharma, Prachi, Shepard, Ron, Shu, Yinan, Staab, Jakob K., Straatsma, Tjerk P., Sørensen, Lasse Kragh, Tenorio, Bruno Nunes Cabral, Truhlar, Donald G., Ungur, Liviu, Vacher, Morgane, Veryazov, Valera, Voß, Torben Arne, Weser, Oskar, Wu, Dihua, Yang, Xuchun, Yarkony, David, Zhou, Chen, Zobel, J Patrick, and Lindh, Roland

Abstract

The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations.

Published
2023

10. The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

Author

Li Manni, Giovanni, primary, Fdez. Galván, Ignacio, additional, Alavi, Ali, additional, Aleotti, Flavia, additional, Aquilante, Francesco, additional, Autschbach, Jochen, additional, Avagliano, Davide, additional, Baiardi, Alberto, additional, Bao, Jie J., additional, Battaglia, Stefano, additional, Birnoschi, Letitia, additional, Blanco-González, Alejandro, additional, Bokarev, Sergey I., additional, Broer, Ria, additional, Cacciari, Roberto, additional, Calio, Paul B., additional, Carlson, Rebecca K., additional, Carvalho Couto, Rafael, additional, Cerdán, Luis, additional, Chibotaru, Liviu F., additional, Chilton, Nicholas F., additional, Church, Jonathan Richard, additional, Conti, Irene, additional, Coriani, Sonia, additional, Cuéllar-Zuquin, Juliana, additional, Daoud, Razan E., additional, Dattani, Nike, additional, Decleva, Piero, additional, de Graaf, Coen, additional, Delcey, Mickaël G., additional, De Vico, Luca, additional, Dobrautz, Werner, additional, Dong, Sijia S., additional, Feng, Rulin, additional, Ferré, Nicolas, additional, Filatov(Gulak), Michael, additional, Gagliardi, Laura, additional, Garavelli, Marco, additional, González, Leticia, additional, Guan, Yafu, additional, Guo, Meiyuan, additional, Hennefarth, Matthew R., additional, Hermes, Matthew R., additional, Hoyer, Chad E., additional, Huix-Rotllant, Miquel, additional, Jaiswal, Vishal Kumar, additional, Kaiser, Andy, additional, Kaliakin, Danil S., additional, Khamesian, Marjan, additional, King, Daniel S., additional, Kochetov, Vladislav, additional, Krośnicki, Marek, additional, Kumaar, Arpit Arun, additional, Larsson, Ernst D., additional, Lehtola, Susi, additional, Lepetit, Marie-Bernadette, additional, Lischka, Hans, additional, López Ríos, Pablo, additional, Lundberg, Marcus, additional, Ma, Dongxia, additional, Mai, Sebastian, additional, Marquetand, Philipp, additional, Merritt, Isabella C. D., additional, Montorsi, Francesco, additional, Mörchen, Maximilian, additional, Nenov, Artur, additional, Nguyen, Vu Ha Anh, additional, Nishimoto, Yoshio, additional, Oakley, Meagan S., additional, Olivucci, Massimo, additional, Oppel, Markus, additional, Padula, Daniele, additional, Pandharkar, Riddhish, additional, Phung, Quan Manh, additional, Plasser, Felix, additional, Raggi, Gerardo, additional, Rebolini, Elisa, additional, Reiher, Markus, additional, Rivalta, Ivan, additional, Roca-Sanjuán, Daniel, additional, Romig, Thies, additional, Safari, Arta Anushirwan, additional, Sánchez-Mansilla, Aitor, additional, Sand, Andrew M., additional, Schapiro, Igor, additional, Scott, Thais R., additional, Segarra-Martí, Javier, additional, Segatta, Francesco, additional, Sergentu, Dumitru-Claudiu, additional, Sharma, Prachi, additional, Shepard, Ron, additional, Shu, Yinan, additional, Staab, Jakob K., additional, Straatsma, Tjerk P., additional, Sørensen, Lasse Kragh, additional, Tenorio, Bruno Nunes Cabral, additional, Truhlar, Donald G., additional, Ungur, Liviu, additional, Vacher, Morgane, additional, Veryazov, Valera, additional, Voß, Torben Arne, additional, Weser, Oskar, additional, Wu, Dihua, additional, Yang, Xuchun, additional, Yarkony, David, additional, Zhou, Chen, additional, Zobel, J. Patrick, additional, and Lindh, Roland, additional

Published
2023
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11. The OpenMolcas Web:A Community-Driven Approach to Advancing Computational Chemistry

Author

Li Manni, Giovanni, Fdez. Galván, Ignacio, Alavi, Ali, Aleotti, Flavia, Aquilante, Francesco, Autschbach, Jochen, Avagliano, Davide, Baiardi, Alberto, Bao, Jie J., Battaglia, Stefano, Birnoschi, Letitia, Blanco-González, Alejandro, Bokarev, Sergey I., Broer, Ria, Cacciari, Roberto, Calio, Paul B., Carlson, Rebecca K., Carvalho Couto, Rafael, Cerdán, Luis, Chibotaru, Liviu F., Chilton, Nicholas F., Church, Jonathan Richard, Conti, Irene, Coriani, Sonia, Cuéllar-Zuquin, Juliana, Daoud, Razan E., Dattani, Nike, Decleva, Piero, de Graaf, Coen, Delcey, Mickaël G., De Vico, Luca, Dobrautz, Werner, Dong, Sijia S., Feng, Rulin, Ferré, Nicolas, Filatov(Gulak), Michael, Gagliardi, Laura, Garavelli, Marco, González, Leticia, Guan, Yafu, Guo, Meiyuan, Hennefarth, Matthew R., Hermes, Matthew R., Hoyer, Chad E., Huix-Rotllant, Miquel, Jaiswal, Vishal Kumar, Kaiser, Andy, Kaliakin, Danil S., Khamesian, Marjan, King, Daniel S., Kochetov, Vladislav, Krośnicki, Marek, Kumaar, Arpit Arun, Larsson, Ernst D., Lehtola, Susi, Lepetit, Marie Bernadette, Lischka, Hans, López Ríos, Pablo, Lundberg, Marcus, Ma, Dongxia, Mai, Sebastian, Marquetand, Philipp, Merritt, Isabella C.D., Montorsi, Francesco, Mörchen, Maximilian, Nenov, Artur, Nguyen, Vu Ha Anh, Nishimoto, Yoshio, Oakley, Meagan S., Olivucci, Massimo, Oppel, Markus, Padula, Daniele, Pandharkar, Riddhish, Phung, Quan Manh, Plasser, Felix, Raggi, Gerardo, Rebolini, Elisa, Reiher, Markus, Rivalta, Ivan, Roca-Sanjuán, Daniel, Romig, Thies, Safari, Arta Anushirwan, Sánchez-Mansilla, Aitor, Sand, Andrew M., Schapiro, Igor, Scott, Thais R., Segarra-Martí, Javier, Segatta, Francesco, Sergentu, Dumitru Claudiu, Sharma, Prachi, Shepard, Ron, Shu, Yinan, Staab, Jakob K., Straatsma, Tjerk P., Sørensen, Lasse Kragh, Tenorio, Bruno Nunes Cabral, Truhlar, Donald G., Ungur, Liviu, Vacher, Morgane, Veryazov, Valera, Voß, Torben Arne, Weser, Oskar, Wu, Dihua, Yang, Xuchun, Yarkony, David, Zhou, Chen, Zobel, J. Patrick, Lindh, Roland, Li Manni, Giovanni, Fdez. Galván, Ignacio, Alavi, Ali, Aleotti, Flavia, Aquilante, Francesco, Autschbach, Jochen, Avagliano, Davide, Baiardi, Alberto, Bao, Jie J., Battaglia, Stefano, Birnoschi, Letitia, Blanco-González, Alejandro, Bokarev, Sergey I., Broer, Ria, Cacciari, Roberto, Calio, Paul B., Carlson, Rebecca K., Carvalho Couto, Rafael, Cerdán, Luis, Chibotaru, Liviu F., Chilton, Nicholas F., Church, Jonathan Richard, Conti, Irene, Coriani, Sonia, Cuéllar-Zuquin, Juliana, Daoud, Razan E., Dattani, Nike, Decleva, Piero, de Graaf, Coen, Delcey, Mickaël G., De Vico, Luca, Dobrautz, Werner, Dong, Sijia S., Feng, Rulin, Ferré, Nicolas, Filatov(Gulak), Michael, Gagliardi, Laura, Garavelli, Marco, González, Leticia, Guan, Yafu, Guo, Meiyuan, Hennefarth, Matthew R., Hermes, Matthew R., Hoyer, Chad E., Huix-Rotllant, Miquel, Jaiswal, Vishal Kumar, Kaiser, Andy, Kaliakin, Danil S., Khamesian, Marjan, King, Daniel S., Kochetov, Vladislav, Krośnicki, Marek, Kumaar, Arpit Arun, Larsson, Ernst D., Lehtola, Susi, Lepetit, Marie Bernadette, Lischka, Hans, López Ríos, Pablo, Lundberg, Marcus, Ma, Dongxia, Mai, Sebastian, Marquetand, Philipp, Merritt, Isabella C.D., Montorsi, Francesco, Mörchen, Maximilian, Nenov, Artur, Nguyen, Vu Ha Anh, Nishimoto, Yoshio, Oakley, Meagan S., Olivucci, Massimo, Oppel, Markus, Padula, Daniele, Pandharkar, Riddhish, Phung, Quan Manh, Plasser, Felix, Raggi, Gerardo, Rebolini, Elisa, Reiher, Markus, Rivalta, Ivan, Roca-Sanjuán, Daniel, Romig, Thies, Safari, Arta Anushirwan, Sánchez-Mansilla, Aitor, Sand, Andrew M., Schapiro, Igor, Scott, Thais R., Segarra-Martí, Javier, Segatta, Francesco, Sergentu, Dumitru Claudiu, Sharma, Prachi, Shepard, Ron, Shu, Yinan, Staab, Jakob K., Straatsma, Tjerk P., Sørensen, Lasse Kragh, Tenorio, Bruno Nunes Cabral, Truhlar, Donald G., Ungur, Liviu, Vacher, Morgane, Veryazov, Valera, Voß, Torben Arne, Weser, Oskar, Wu, Dihua, Yang, Xuchun, Yarkony, David, Zhou, Chen, Zobel, J. Patrick, and Lindh, Roland

Abstract

The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations.

Published
2023

12. Core-level nonlinear spectroscopy triggered by stochastic X-ray pulses

Author

Kayser, Yves, Milne, Chris, Juranić, Pavle, Sala, Leonardo, Czapla-Masztafiak, Joanna, Follath, Rolf, Kavčič, Matjaž, Knopp, Gregor, Rehanek, Jens, Błachucki, Wojciech, Delcey, Mickaël G., Lundberg, Marcus, Tyrała, Krzysztof, Zhu, Diling, Alonso-Mori, Roberto, Abela, Rafael, Sá, Jacinto, and Szlachetko, Jakub

Published
2019
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13. Exact semi-classical light–matter interaction operator applied to two-photon processes with strong relativistic effects.

Author

Delcey, Mickaël G., Couto, Rafael Carvalho, Sørensen, Lasse Kragh, Fdez. Galván, Ignacio, Guo, Meiyuan, Lindh, Roland, and Lundberg, Marcus

Subjects
*INELASTIC scattering, *X-ray scattering, *MAGNITUDE (Mathematics), *PHOTON scattering, *ENERGY level transitions, *PHOTONS, *WAVELENGTHS
Abstract

X-ray processes involve interactions with high-energy photons. For these short wavelengths, the perturbing field cannot be treated as constant, and there is a need to go beyond the electric-dipole approximation. The exact semi-classical light–matter interaction operator offers several advantages compared to the multipole expansion such as improved stability and ease of implementation. Here, the exact operator is used to model x-ray scattering in metal K pre-edges. This is a relativistic two-photon process where absorption is dominated by electric-dipole forbidden transitions. With the restricted active space state-interaction approach, spectra can be calculated even for the multiconfigurational wavefunctions including second-order perturbation. However, as the operator itself depends on the transition energy, the cost for evaluating integrals for hundreds of thousands unique transitions becomes a bottleneck. Here, this is solved by calculating the integrals in a molecular-orbital basis that only runs over the active space, combined with a grouping scheme where the operator is the same for close-lying transitions. This speeds up the calculations of single-photon processes and is critical for the modeling of two-photon scattering processes. The new scheme is used to model Kα resonant inelastic x-ray scattering of iron–porphyrin complexes with relevance to studies of heme enzymes, for which the total computational time is reduced by several orders of magnitude with an effect on transition intensities of 0.1% or less. [ABSTRACT FROM AUTHOR]

Published
2020
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14. Soft X-ray signatures of cationic manganese-oxo systems, including a high-spin manganese(v) complex

Author

Delcey, Mickaël G., Lindblad, Rebecka, Timm, Martin, Bülow, Christine, Zamudio-Bayer, Vicente, von Issendorff, Bernd, Lau, J. Tobias, Lundberg, Marcus, Delcey, Mickaël G., Lindblad, Rebecka, Timm, Martin, Bülow, Christine, Zamudio-Bayer, Vicente, von Issendorff, Bernd, Lau, J. Tobias, and Lundberg, Marcus

Abstract

Manganese–oxo species catalyze key reactions, including C–H bond activation or dioxygen formation in natural photosynthesis. To better understand relevant reaction intermediates, we characterize electronic states and geometric structures of [MnOn]+ manganese–oxo complexes that represent a wide range of manganese oxidation states. To this end, we apply soft X-ray spectroscopy in a cryogenic ion trap, combined with multiconfigurational wavefunction calculations. We identify [MnO2]+ as a rare high-spin manganese(V) oxo complex with key similarities to six-coordinated manganese(V) oxo systems that are proposed as reaction intermediates in catalytic dioxygen bond formation.

Published
2022
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16. Toward a Computational Ecotoxicity Assay

Author

Kamerlin, Natasha, Delcey, Mickaël G, Manzetti, Sergio, Van der Spoel, David, Kamerlin, Natasha, Delcey, Mickaël G, Manzetti, Sergio, and Van der Spoel, David

Abstract

Thousands of anthropogenic chemicals are released into the environment each year, posing potential hazards to human and environmental health. Toxic chemicals may cause a variety of adverse health effects, triggering immediate symptoms or delayed effects over longer periods of time. It is thus crucial to develop methods that can rapidly screen and predict the toxicity of chemicals to limit the potential harmful impacts of chemical pollutants. Computational methods are being increasingly used in toxicity predictions. Here, the method of molecular docking is assessed for screening potential toxicity of a variety of xenobiotic compounds, including pesticides, pharmaceuticals, pollutants, and toxins derived from the chemical industry. The method predicts the binding energy of pollutants to a set of carefully selected receptors under the assumption that toxicity in many cases is related to interference with biochemical pathways. The strength of the applied method lies in its rapid generation of interaction maps between potential toxins and the targeted enzymes, which could quickly yield molecular-level information and insight into potential perturbation pathways, aiding in the prioritization of chemicals for further tests. Two scoring functions are compared: Autodock Vina and the machine-learning scoring function RF-Score-VS. The results are promising, although hampered by the accuracy of the scoring functions. The strengths and weaknesses of the docking protocol are discussed, as well as future directions for improving the accuracy for the purpose of toxicity predictions., Computational Ecotoxicology

Published
2020
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21. OpenMolcas : From Source Code to Insight

Author

Galván, Ignacio Fdez., Vacher, Morgane, Alavi, Ali, Angeli, Celestino, Aquilante, Francesco, Autschbach, Jochen, Bao, Jie J., Bokarev, Sergey I., Bogdanov, Nikolay A., Carlson, Rebecca K., Chibotaru, Liviu F., Creutzberg, Joel, Dattani, Nike, Delcey, Mickaël G., Dong, Sijia S., Dreuw, Andreas, Freitag, Leon, Manuel Frutos, Luis, Gagliardi, Laura, Gendron, Frédéric, Giussani, Angelo, González, Leticia, Grell, Gilbert, Guo, Meiyuan, Hoyer, Chad E., Johansson, Marcus, Keller, Sebastian, Knecht, Stefan, Kovačević, Goran, Källman, Erik, Li Manni, Giovanni, Lundberg, Marcus, Ma, Yingjin, Mai, Sebastian, Malhado, João Pedro, Malmqvist, Per Åke, Marquetand, Philipp, Mewes, Stefanie A., Norell, Jesper, Olivucci, Massimo, Oppel, Markus, Quan, Manh, Pierloot, Kristine, Plasser, Felix, Reiher, Markus, Sand, Andrew M., Schapiro, Igor, Sharma, Prachi, Stein, Christopher J., Sørensen, Lasse Kragh, Truhlar, Donald G., Ugandi, Mihkel, Ungur, Liviu, Valentini, Alessio, Vancoillie, Steven, Veryazov, Valera, Weser, Oskar, Wesołowski, Tomasz A., Widmark, Per-Olof, Wouters, Sebastian, Zech, Alexander, Zobel, J. Patrick, Lindh, Roland, Galván, Ignacio Fdez., Vacher, Morgane, Alavi, Ali, Angeli, Celestino, Aquilante, Francesco, Autschbach, Jochen, Bao, Jie J., Bokarev, Sergey I., Bogdanov, Nikolay A., Carlson, Rebecca K., Chibotaru, Liviu F., Creutzberg, Joel, Dattani, Nike, Delcey, Mickaël G., Dong, Sijia S., Dreuw, Andreas, Freitag, Leon, Manuel Frutos, Luis, Gagliardi, Laura, Gendron, Frédéric, Giussani, Angelo, González, Leticia, Grell, Gilbert, Guo, Meiyuan, Hoyer, Chad E., Johansson, Marcus, Keller, Sebastian, Knecht, Stefan, Kovačević, Goran, Källman, Erik, Li Manni, Giovanni, Lundberg, Marcus, Ma, Yingjin, Mai, Sebastian, Malhado, João Pedro, Malmqvist, Per Åke, Marquetand, Philipp, Mewes, Stefanie A., Norell, Jesper, Olivucci, Massimo, Oppel, Markus, Quan, Manh, Pierloot, Kristine, Plasser, Felix, Reiher, Markus, Sand, Andrew M., Schapiro, Igor, Sharma, Prachi, Stein, Christopher J., Sørensen, Lasse Kragh, Truhlar, Donald G., Ugandi, Mihkel, Ungur, Liviu, Valentini, Alessio, Vancoillie, Steven, Veryazov, Valera, Weser, Oskar, Wesołowski, Tomasz A., Widmark, Per-Olof, Wouters, Sebastian, Zech, Alexander, Zobel, J. Patrick, and Lindh, Roland

Abstract

In this Article we describe the OpenMolcas environment and invite the computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during the transition from the commercial MOLCAS product to the open-source platform. The paper initially describes the technical details of the new software development platform. This is followed by brief presentations of many new methods, implementations, and features of the OpenMolcas program suite. These developments include novel wave function methods such as stochastic complete active space self-consistent field, density matrix renormalization group (DMRG) methods, and hybrid multiconfigurational wave function and density functional theory models. Some of these implementations include an array of additional options and functionalities. The paper proceeds and describes developments related to explorations of potential energy surfaces. Here we present methods for the optimization of conical intersections, the simulation of adiabatic and nonadiabatic molecular dynamics, and interfaces to tools for semiclassical and quantum mechanical nuclear dynamics. Furthermore, the Article describes features unique to simulations of spectroscopic and magnetic phenomena such as the exact semiclassical description of the interaction between light and matter, various X-ray processes, magnetic circular dichroism, and properties. Finally, the paper describes a number of built-in and add-on features to support the OpenMolcas platform with postcalculation analysis and visualization, a multiscale simulation option using frozen-density embedding theory, and new electronic and muonic basis sets.

Published
2019
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22. OpenMolcas: From Source Code to Insight

Author

Fdez. Galván, Ignacio, primary, Vacher, Morgane, additional, Alavi, Ali, additional, Angeli, Celestino, additional, Aquilante, Francesco, additional, Autschbach, Jochen, additional, Bao, Jie J., additional, Bokarev, Sergey I., additional, Bogdanov, Nikolay A., additional, Carlson, Rebecca K., additional, Chibotaru, Liviu F., additional, Creutzberg, Joel, additional, Dattani, Nike, additional, Delcey, Mickaël G., additional, Dong, Sijia S., additional, Dreuw, Andreas, additional, Freitag, Leon, additional, Frutos, Luis Manuel, additional, Gagliardi, Laura, additional, Gendron, Frédéric, additional, Giussani, Angelo, additional, González, Leticia, additional, Grell, Gilbert, additional, Guo, Meiyuan, additional, Hoyer, Chad E., additional, Johansson, Marcus, additional, Keller, Sebastian, additional, Knecht, Stefan, additional, Kovačević, Goran, additional, Källman, Erik, additional, Li Manni, Giovanni, additional, Lundberg, Marcus, additional, Ma, Yingjin, additional, Mai, Sebastian, additional, Malhado, João Pedro, additional, Malmqvist, Per Åke, additional, Marquetand, Philipp, additional, Mewes, Stefanie A., additional, Norell, Jesper, additional, Olivucci, Massimo, additional, Oppel, Markus, additional, Phung, Quan Manh, additional, Pierloot, Kristine, additional, Plasser, Felix, additional, Reiher, Markus, additional, Sand, Andrew M., additional, Schapiro, Igor, additional, Sharma, Prachi, additional, Stein, Christopher J., additional, Sørensen, Lasse Kragh, additional, Truhlar, Donald G., additional, Ugandi, Mihkel, additional, Ungur, Liviu, additional, Valentini, Alessio, additional, Vancoillie, Steven, additional, Veryazov, Valera, additional, Weser, Oskar, additional, Wesołowski, Tomasz A., additional, Widmark, Per-Olof, additional, Wouters, Sebastian, additional, Zech, Alexander, additional, Zobel, J. Patrick, additional, and Lindh, Roland, additional

Published
2019
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23. Restricted active space calculations of L-edge X-ray absorption spectra: From molecular orbitals to multiplet states.

Author

Pinjari, Rahul V., Delcey, Mickaël G., Guo, Meiyuan, Odelius, Michael, and Lundberg, Marcus

Subjects
*MOLECULAR orbitals, *X-ray spectra, *CHARGE transfer, *LIGANDS (Chemistry), *ABSORPTION spectra, *ELECTRON-electron interactions, *SPIN-orbit interactions
Abstract

The metal L-edge (2p → 3d) X-ray absorption spectra are affected by a number of different interactions: electron-electron repulsion, spin-orbit coupling, and charge transfer between metal and ligands, which makes the simulation of spectra challenging. The core restricted active space (RAS) method is an accurate and flexible approach that can be used to calculate X-ray spectra of a wide range of medium-sized systems without any symmetry constraints. Here, the applicability of the method is tested in detail by simulating three ferric (3d5) model systems with well-known electronic structure, viz., atomic Fe3+, high-spin [FeCl6]³- with ligand donor bonding, and low-spin [Fe(CN)6]3- that also has metal backbonding. For these systems, the performance of the core RAS method, which does not require any system-dependent parameters, is comparable to that of the commonly used semi-empirical charge-transfer multiplet model. It handles orbitally degenerate ground states, accurately describes metal-ligand interactions, and includes both single and multiple excitations. The results are sensitive to the choice of orbitals in the active space and this sensitivity can be used to assign spectral features. A method has also been developed to analyze the calculated X-ray spectra using a chemically intuitive molecular orbital picture. [ABSTRACT FROM AUTHOR]

Published
2014
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24. Analytical gradients of complete active space self-consistent field energies using Cholesky decomposition: Geometry optimization and spin-state energetics of a ruthenium nitrosyl complex.

Author

Delcey, Mickaël G., Freitag, Leon, Pedersen, Thomas Bondo, Aquilante, Francesco, Lindh, Roland, and González, Leticia

Subjects
*BIOENERGETICS, *RUTHENIUM compounds, *MATHEMATICAL optimization, *DENSITY functional theory, *QUANTUM perturbations
Abstract

We present a formulation of analytical energy gradients at the complete active space self-consistent field (CASSCF) level of theory employing density fitting (DF) techniques to enable efficient geometry optimizations of large systems. As an example, the ground and lowest triplet state geometries of a ruthenium nitrosyl complex are computed at the DF-CASSCF level of theory and compared with structures obtained from density functional theory (DFT) using the B3LYP, BP86, and M06L functionals. The average deviation of all bond lengths compared to the crystal structure is 0.042 Å at the DF-CASSCF level of theory, which is slightly larger but still comparable with the deviations obtained by the tested DFT functionals, e.g., 0.032 Å with M06L. Specifically, the root-mean-square deviation between the DF-CASSCF and best DFT coordinates, delivered by BP86, is only 0.08 Å for S0 and 0.11 Å for T1, indicating that the geometries are very similar. While keeping the mean energy gradient errors below 0.25%, the DF technique results in a 13-fold speedup compared to the conventional CASSCF geometry optimization algorithm. Additionally, we assess the singlet-triplet energy vertical and adiabatic differences with multiconfigurational second-order perturbation theory (CASPT2) using the DF-CASSCF and DFT optimized geometries. It is found that the vertical CASPT2 energies are relatively similar regardless of the geometry employed whereas the adiabatic singlet-triplet gaps are more sensitive to the chosen triplet geometry. [ABSTRACT FROM AUTHOR]

Published
2014
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25. Cost and sensitivity of restricted active-space calculations of metal L-edge X-ray absorption spectra

Author

Pinjari, Rahul V., Delcey, Mickaël G., Guo, Meiyuan, Odelius, Michael, and Lundberg, Marcus

Subjects
transition metals, X-ray absorption spectroscopy, multiconfigurational wavefunction, spin-orbit coupling, charge transfer, Teoretisk kemi, Theoretical Chemistry
Abstract

The restricted active-space (RAS) approach can accurately simulate metal L-edge X-ray absorption spectra of first-row transition metal complexes without the use of any fitting parameters. These characteristics provide a unique capability to identify unknown chemical species and to analyze their electronic structure. To find the best balance between cost and accuracy, the sensitivity of the simulated spectra with respect to the method variables has been tested for two models, [FeCl6](3-) and [Fe(CN)(6)](3-). For these systems, the reference calculations give deviations, when compared with experiment, of 1 eV in peak positions, 30% for the relative intensity of major peaks, and 50% for minor peaks. When compared with these deviations, the simulated spectra are sensitive to the number of final states, the inclusion of dynamical correlation, and the ionization potential electron affinity shift, in addition to the selection of the active space. The spectra are less sensitive to the quality of the basis set and even a double- basis gives reasonable results. The inclusion of dynamical correlation through second-order perturbation theory can be done efficiently using the state-specific formalism without correlating the core orbitals. Although these observations are not directly transferable to other systems, they can, together with a cost analysis, aid in the design of RAS models and help to extend the use of this powerful approach to a wider range of transition metal systems. QC 20210505

Published
2016

27. Extending the Reach of Accurate Wavefunction Methods

Author

Delcey, Mickaël G.

Subjects
Photochemistry, Teoretisk kemi, X-ray spectroscopy, Density fitting, Theoretical Chemistry, CASSCF, Quantum chemistry, Analytical gradients
Abstract

Multiconfigurational quantum chemistry methods, and especially the multiconfigurational self-consistent field (MCSCF) and multireference perturbation theory (MRPT2), are powerful tools, particularly suited to the accurate modeling of photochemical processes and transition metal catalysis. However, they are limited by their high computational cost compared to other methods, especially density functional theory. Moreover, there are areas where they would be expected to perform well, but where they are not applied due to lack of experience. This thesis addresses those issues. First, the efficiency of the Cholesky decomposition approximation to reduce the cost of MCSCF and MRPT2 without sacrificing their accuracy is demonstrated. This then motivates the extension of the Cholesky approximation to the computation of MCSCF nuclear gradients, thus strongly improving the ability to perform MCSCF non-adiabatic molecular dynamics. Typically, a tenfold speed-up is observed allowing dynamic simulation of larger systems or over longer times. Finally, multiconfigurational methods are applied to the computation of X-ray spectra of transition metal complexes. The importance of the different parameters in the calculation is systematically investigated, laying the base for wider applications of those accurate methods in the modeling of X-ray spectroscopy. A tool to analyze the resulting spectrum in terms of molecular orbitals is also presented, strengthening the interplay between theory and experiments. With these developments and other significant ones that have happened in recent years, multiconfigurational methods can now reach new grounds and contribute to important new discoveries QC 20210216

Published
2015

28. Simulations of iron K pre-edge X-ray absorption spectra using the restricted active space method

Author

Guo, Meiyuan, Sörensen, Lasse Kragh, Delcey, Mickaël G., Pinjari, Rahul V., Lundberg, Marcus, Guo, Meiyuan, Sörensen, Lasse Kragh, Delcey, Mickaël G., Pinjari, Rahul V., and Lundberg, Marcus

Abstract

The intensities and relative energies of metal K pre-edge features are sensitive to both geometric and electronic structures. With the possibility to collect high-resolution spectral data it is important to find theoretical methods that include all important spectral effects: ligand-field splitting, multiplet structures, 3d-4p orbital hybridization, and charge-transfer excitations. Here the restricted active space (RAS) method is used for the first time to calculate metal K pre-edge spectra of open-shell systems, and its performance is tested against on six iron complexes: [FeCl6](n-), [FeCl4](n-), and [Fe(CN)(6)](n-) in ferrous and ferric oxidation states. The method gives good descriptions of the spectral shapes for all six systems. The mean absolute deviation for the relative energies of different peaks is only 0.1 eV. For the two systems that lack centrosymmetry [FeCl4](2-/1-), the ratios between dipole and quadrupole intensity contributions are reproduced with an error of 10%, which leads to good descriptions of the integrated pre-edge intensities. To gain further chemical insight, the origins of the pre-edge features have been analyzed with a chemically intuitive molecular orbital picture that serves as a bridge between the spectra and the electronic structures. The pre-edges contain information about both ligand-field strengths and orbital covalencies, which can be understood by analyzing the RAS wavefunction. The RAS method can thus be used to predict and rationalize the effects of changes in both the oxidation state and ligand environment in a number of hard X-ray studies of small and medium-sized molecular systems.

Published
2016
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29. Molecular orbital simulations of metal 1s2p resonant inelastic X-ray scattering

Author

Guo, Meiyuan, Erik, Källman, Sørensen, Lasse Kragh, Delcey, Mickaël G., Pinjari, Rahul V., Lundberg, Marcus, Guo, Meiyuan, Erik, Källman, Sørensen, Lasse Kragh, Delcey, Mickaël G., Pinjari, Rahul V., and Lundberg, Marcus

Abstract

For first-row transition metals, high-resolution 3d electronic structure information can be obtained using resonant inelastic X-ray scattering (RIXS). In the hard X-ray region, a K pre-edge (1s -> 3d) excitation can be followed by monitoring the dipole-allowed K alpha (2p -> 1s) or K beta (3p -> 1s) emission, processes labeled 1s2p or 1s3p RIXS. Here the restricted active space (RAS) approach, which is a molecular orbital method, is used for the first time to study hard X-ray RIXS processes. This is achieved by including the two sets of core orbitals in different partitions of the active space. Transition intensities are calculated using both first- and second-order expansions of the wave vector, including, but not limited to, electric dipoles and quadrupoles. The accuracy of the approach is tested for 1s2p RIXS of iron hexacyanides [Fe(CN)(6)](n-) in ferrous and ferric oxidation states. RAS simulations accurately describe the multiplet structures and the role of 2p and 3d spin-orbit coupling on energies and selection rules. Compared to experiment, relative energies of the two [Fe(CN)(6)](3-) resonances deviate by 0.2 eV in both incident energy and energy transfer directions, and multiplet splittings in [Fe(CN)(6)](4-) are reproduced within 0.1 eV. These values are similar to what can be expected for valence excitations. The development opens the modeling of hard X-ray scattering processes for both solution catalysts and enzymatic systems.

Published
2016
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30. Viewing the Valence Electronic Structure of Ferric and Ferrous Hexacyanide in Solution from the Fe and Cyanide Perspectives

Author

Kunnus, Kristjan, Zhang, Wenkai, Delcey, Mickaël G., Pinjari, Rahul V., Miedema, Piter S., Schreck, Simon, Quevedo, Wilson, Schröder, Henning, Foehlisch, Alexander, Gaffney, Kelly J., Lundberg, Marcus, Odelius, Michael, Wernet, Philippe, Kunnus, Kristjan, Zhang, Wenkai, Delcey, Mickaël G., Pinjari, Rahul V., Miedema, Piter S., Schreck, Simon, Quevedo, Wilson, Schröder, Henning, Foehlisch, Alexander, Gaffney, Kelly J., Lundberg, Marcus, Odelius, Michael, and Wernet, Philippe

Abstract

The valence-excited states of ferric and ferrous hexacyanide ions in aqueous solution were mapped by resonant inelastic X-ray scattering (RIXS) at the Fe L-2,L-3 and N K edges. Probing of both the central Fe and the ligand N atoms enabled identification of the metal-and ligand-centered excited states, as well as ligand-to-metal and metal-to-ligand charge-transfer excited states. Ab initio calculations utilizing the RASPT2 method were used to simulate the Fe L-2,L-3-edge RIXS spectra and enabled quantification of the covalencies of both occupied and empty orbitals of pi and sigma symmetry. We found that pi back-donation in the ferric complex is smaller than that in the ferrous complex. This is evidenced by the relative amounts of Fe 3d character in the nominally 2 pi CN- molecular orbital of 7% and 9% in ferric and ferrous hexacyanide, respectively. Utilizing the direct sensitivity of Fe L-3-edge RIXS to the Fe 3d character in the occupied molecular orbitals, we also found that the donation interactions are dominated by sigma bonding. The latter was found to be stronger in the ferric complex, with an Fe 3d contribution to the nominally 5 sigma CN- molecular orbitals of 29% compared to 20% in the ferrous complex. These results are consistent with the notion that a higher charge at the central metal atom increases donation and decreases back-donation., QC 20210505

Published
2016
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31. MOLCAS 8:new capabilities for multiconfigurational quantum chemical calculations across the periodic table

Author

Aquilante, Francesco, Autschbach, Jochen, Carlson, Rebecca K., Chibotaru, Liviu F., Delcey, Mickaël G., De Vico, Luca, Fdez. Galván, Ignacio, Ferré, Nicolas, Frutos, Luis Manuel, Gagliardi, Laura, Garavelli, Marco, Giussani, Angelo, Hoyer, Chad E., Li Manni, Giovanni, Lischka, Hans, Ma, Dongxia, Malmqvist, Per Åke, Müller, Thomas, Nenov, Artur, Olivucci, Massimo, Pedersen, Thomas Bondo, Peng, Daoling, Plasser, Felix, Pritchard, Ben, Reiher, Markus, Rivalta, Ivan, Schapiro, Igor, Segarra-Martí, Javier, Stenrup, Michael, Truhlar, Donald G., Ungur, Liviu, Valentini, Alessio, Vancoillie, Steven, Veryazov, Valera, Vysotskiy, Victor P., Weingart, Oliver, Zapata, Felipe, Lindh, Roland, Aquilante, Francesco, Autschbach, Jochen, Carlson, Rebecca K., Chibotaru, Liviu F., Delcey, Mickaël G., De Vico, Luca, Fdez. Galván, Ignacio, Ferré, Nicolas, Frutos, Luis Manuel, Gagliardi, Laura, Garavelli, Marco, Giussani, Angelo, Hoyer, Chad E., Li Manni, Giovanni, Lischka, Hans, Ma, Dongxia, Malmqvist, Per Åke, Müller, Thomas, Nenov, Artur, Olivucci, Massimo, Pedersen, Thomas Bondo, Peng, Daoling, Plasser, Felix, Pritchard, Ben, Reiher, Markus, Rivalta, Ivan, Schapiro, Igor, Segarra-Martí, Javier, Stenrup, Michael, Truhlar, Donald G., Ungur, Liviu, Valentini, Alessio, Vancoillie, Steven, Veryazov, Valera, Vysotskiy, Victor P., Weingart, Oliver, Zapata, Felipe, and Lindh, Roland

Abstract

In this report, we summarize and describe the recent unique updates and additions to the Molcas quantum chemistry program suite as contained in release version 8. These updates include natural and spin orbitals for studies of magnetic properties, local and linear scaling methods for the Douglas-Kroll-Hess transformation, the generalized active space concept in MCSCF methods, a combination of multiconfigurational wave functions with density functional theory in the MC-PDFT method, additional methods for computation of magnetic properties, methods for diabatization, analytical gradients of state average complete active space SCF in association with density fitting, methods for constrained fragment optimization, large-scale parallel multireference configuration interaction including analytic gradients via the interface to the Columbus package, and approximations of the CASPT2 method to be used for computations of large systems. In addition, the report includes the description of a computational machinery for nonlinear optical spectroscopy through an interface to the QM/MM package Cobramm. Further, a module to run molecular dynamics simulations is added, two surface hopping algorithms are included to enable nonadiabatic calculations, and the DQ method for diabatization is added. Finally, we report on the subject of improvements with respects to alternative file options and parallelization.

Published
2016

33. Viewing the Valence Electronic Structure of Ferric and Ferrous Hexacyanide in Solution from the Fe and Cyanide Perspectives

Author

Kunnus, Kristjan, primary, Zhang, Wenkai, additional, Delcey, Mickaël G., additional, Pinjari, Rahul V., additional, Miedema, Piter S., additional, Schreck, Simon, additional, Quevedo, Wilson, additional, Schröder, Henning, additional, Föhlisch, Alexander, additional, Gaffney, Kelly J., additional, Lundberg, Marcus, additional, Odelius, Michael, additional, and Wernet, Philippe, additional

Published
2016
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37. Analytical gradients of the state-average complete active space self-consistent field method with density fitting

Author

Delcey, Mickaël G., Pedersen, Thomas Bondo, Aquilante, Francesco, Lindh, Roland, Delcey, Mickaël G., Pedersen, Thomas Bondo, Aquilante, Francesco, and Lindh, Roland

Abstract

An efficient implementation of the state-averaged complete active space self-consistent field (SA-CASSCF) gradients employing density fitting (DF) is presented. The DF allows a reduction both in scaling and prefactors of the different steps involved. The performance of the algorithm is demonstrated on a set of molecules ranging up to an iron-Heme b complex which with its 79 atoms and 811 basis functions is to our knowledge the largest SA-CASSCF gradient computed. For smaller systems where the conventional code could still be used as a reference, both the linear response calculation and the gradient formation showed a clear timing reduction and the overall cost of a geometry optimization is typically reduced by more than one order of magnitude while the accuracy loss is negligible.

Published
2015
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38. Orbital entanglement and CASSCF analysis of the Ru-NO bond in a Ruthenium nitrosyl complex

Author

Freitag, Leon, Knecht, Stefan, Keller, Sebastian F., Delcey, Mickaël G., Aquilante, Francesco, Pedersen, Thomas Bondo, Lindh, Roland, Reiher, Markus, Gonzalez, Leticia, Freitag, Leon, Knecht, Stefan, Keller, Sebastian F., Delcey, Mickaël G., Aquilante, Francesco, Pedersen, Thomas Bondo, Lindh, Roland, Reiher, Markus, and Gonzalez, Leticia

Abstract

Complete active space self-consistent field (CASSCF) wavefunctions and an orbital entanglement analysis obtained from a density-matrix renormalisation group (DMRG) calculation are used to understand the electronic structure, and, in particular, the Ru-NO bond of a Ru nitrosyl complex. Based on the configurations and orbital occupation numbers obtained for the CASSCF wavefunction and on the orbital entropy measurements evaluated for the DMRG wavefunction, we unravel electron correlation effects in the Ru coordination sphere of the complex. It is shown that Ru-NO pi bonds show static and dynamic correlation, while other Ru-ligand bonds feature predominantly dynamic correlation. The presence of static correlation requires the use of multiconfigurational methods to describe the Ru-NO bond. Subsequently, the CASSCF wavefunction is analysed in terms of configuration state functions based on localised orbitals. The analysis of the wavefunctions in the electronic singlet ground state and the first triplet state provides a picture of the Ru-NO moiety beyond the standard representation based on formal oxidation states. A distinct description of the Ru and NO fragments is advocated. The electron configuration of Ru is an equally weighted superposition of Ru-II and Ru-III configurations, with the Ru-III configuration originating from charge donation mostly from Cl ligands. However, and contrary to what is typically assumed, the electronic configuration of the NO ligand is best described as electroneutral.

Published
2015
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40. WARNING: The light-emitting molecular structures responsible for the chemiluminescence and fluorescence phenomena are not necessarily the same!

Author

Roca-Sanjuán, Daniel, Delcey, Mickaël G., Navizet, Isabelle, Ferré, Nicolas, Liu, Ya-Jun, Lindh, Roland, Instituto de Ciencia Molecular (ICMol), Universitat de València (UV), Department of Chemistry-Angstrom, the Theoretical Chemistry Programme, Uppsala University, Université Paris-Est (UPE), Institut de Chimie Radicalaire (ICR), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University (BNU), and Siri, Didier

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [CHIM.THEO] Chemical Sciences/Theoretical and/or physical chemistry
Abstract

WOS:000305280700103; International audience; no abstract

Published
2012

41. Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table

Author

Aquilante, Francesco, primary, Autschbach, Jochen, additional, Carlson, Rebecca K., additional, Chibotaru, Liviu F., additional, Delcey, Mickaël G., additional, De Vico, Luca, additional, Fdez. Galván, Ignacio, additional, Ferré, Nicolas, additional, Frutos, Luis Manuel, additional, Gagliardi, Laura, additional, Garavelli, Marco, additional, Giussani, Angelo, additional, Hoyer, Chad E., additional, Li Manni, Giovanni, additional, Lischka, Hans, additional, Ma, Dongxia, additional, Malmqvist, Per Åke, additional, Müller, Thomas, additional, Nenov, Artur, additional, Olivucci, Massimo, additional, Pedersen, Thomas Bondo, additional, Peng, Daoling, additional, Plasser, Felix, additional, Pritchard, Ben, additional, Reiher, Markus, additional, Rivalta, Ivan, additional, Schapiro, Igor, additional, Segarra‐Martí, Javier, additional, Stenrup, Michael, additional, Truhlar, Donald G., additional, Ungur, Liviu, additional, Valentini, Alessio, additional, Vancoillie, Steven, additional, Veryazov, Valera, additional, Vysotskiy, Victor P., additional, Weingart, Oliver, additional, Zapata, Felipe, additional, and Lindh, Roland, additional

Published
2015
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47. Accurate calculations of geometries and singlet-triplet energy differences for active-site models of [NiFe] hydrogenase

Author

Delcey, Mickaël G., Pierloot, Kristine, Phung, Quan M., Vancoillie, Steven, Lindh, Roland, Ryde, Ulf, Delcey, Mickaël G., Pierloot, Kristine, Phung, Quan M., Vancoillie, Steven, Lindh, Roland, and Ryde, Ulf

Abstract

We have studied the geometry and singlet-triplet energy difference of two mono-nuclear Ni2+ models related to the active site in [NiFe] hydrogenase. Multiconfigurational second-order perturbation theory based on a complete active-space wavefunction with an active space of 12 electrons in 12 orbitals, CASPT2(12,12), reproduces experimental bond lengths to within 1 pm. Calculated singlet-triplet energy differences agree with those obtained from coupled-cluster calculations with single, double and (perturbatively treated) triple excitations (CCSD(T)) to within 12 kJ mol(-1). For a bimetallic model of the active site of [NiFe] hydrogenase, the CASPT2(12,12) results were compared with the results obtained with an extended active space of 22 electrons in 22 orbitals. This is so large that we need to use restricted active-space theory (RASPT2). The calculations predict that the singlet state is 48-57 kJ mol(-1) more stable than the triplet state for this model of the Ni-Sl(a) state. However, in the [NiFe] hydrogenase protein, the structure around the Ni ion is far from the square-planar structure preferred by the singlet state. This destabilises the singlet state so that it is only similar to 24 kJ mol(-1) more stable than the triplet state. Finally, we have studied how various density functional theory methods compare to the experimental, CCSD(T), CASPT2, and RASPT2 results. Semi-local functionals predict the best singlet-triplet energy differences, with BP86, TPSS, and PBE giving mean unsigned errors of 12-13 kJ mol(-1) (maximum errors of 25-31 kJ mol(-1)) compared to CCSD(T). For bond lengths, several methods give good results, e. g. TPSS, BP86, and M06, with mean unsigned errors of 2 pm for the bond lengths if relativistic effects are considered.

Published
2014
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48. Revisiting H2O Nucleation around Au+ and Hg2+ : The Peculiar 'Pseudo-Soft' Character of the Gold Cation

Author

Chaudret, Robin, Contreras-Garcia, Julia, Delcey, Mickaël G., Parisel, Olivier, Yang, Weitao, Piquemal, Jean-Philip, Chaudret, Robin, Contreras-Garcia, Julia, Delcey, Mickaël G., Parisel, Olivier, Yang, Weitao, and Piquemal, Jean-Philip

Abstract

In this contribution, we propose a deeper understanding of the electronic effects affecting the nucleation of water around the Au+ and Hg2+ metal cations using quantum chemistry. To do so, and in order to go beyond usual energetical studies, we make extensive use of state of the art quantum interpretative techniques combining ELF/NCI/QTAIM/EDA computations to capture all ranges of interactions stabilizing the well characterized microhydrated structures. The Electron Localization Function (ELF) topological analysis reveals the peculiar role of the Au+ outer-shell core electrons (subvalence) that appear already spatially preorganized once the addition of the first water molecule occurs. Thus, despite the addition of other water molecules, the electronic structure of Au(H2O)(+) appears frozen due to relativistic effects leading to a maximal acceptation of only two waters in gold's first hydration shell. As the values of the QTAIM (Quantum Theory of Atoms in Molecules) cations's charge is discussed, the Non Covalent Interactions (NCI) analysis showed that Au+ appears still able to interact through longer range van der Waals interaction with the third or fourth hydration shell water molecules. As these types of interaction are not characteristic of either a hard or soft metal cation, we introduced the concept of a "pseudo-soft" cation to define Au+ behavior. Then, extending the study, we performed the same computations replacing Au+ with Hg2+, an isoelectronic cation. If Hg2+ behaves like Au+ for small water clusters, a topological, geometrical, and energetical transition appears when the number of water molecules increases. Regarding the HSAB theory, this transition is characteristic of a shift of Hg2+ from a pseudosoft form to a soft ion and appears to be due to a competition between the relativistic and correlation effects. Indeed, if relativistic effects are predominant, then mercury will behave like gold and have a similar subvalence/geometry; otherwise when correla, QC 20210216

Published
2014
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