Search

Computational chemistry has made tremendous impact on the development of zeolite materials. Molecular dynamics (MD), Monte Carlo (MC), quantum chemistry (QC), and quantum chemical molecular dynamics (QCMD) methods have been applied to the studies of diffusion processes, adsorption characteristics, catalytic reaction mechanism, synthesis processes, acidic properties, etc. in zeolite materials. However, these traditional approaches are not able to accommodate complicated realistic systems because of their approximations and of the limitation of calculation models. To establish a novel computational chemistry approach for exploring new physico-chemical properties of zeolite materials, we have developed a novel dual ensemble MD (DEMD) program and original tight-binding QCMD program, ‘Colors’. The DEMD program can perform the permeation and separation dynamics simulation considering the gradient of chemical potential in a simulation cell. Colors program is over 5000 times faster than the traditional first-principles QCMD simulator. Hence, it enables us to employ more realistic large-scale models. Furthermore, we have also performed large-scale QC calculations based on the density functional theory (DFT) with a whole unit cell model of a zeolite material considering the periodic boundary condition (PBC). In this review, we put forward the application of our novel theoretical approaches for studying physico-chemical properties of zeolite materials.

ATP binding subunit is known as a subunit of ABC transporter, providing energy through the binding of ATP with the subunit and the subsequent hydrolysis reaction of the bound ATP. In this study, density functional theory (DFT) method was used to study the ATP hydrolysis reaction in HisP protein, an ATP binding subunit of Histidine permease HisQMP2, by considering the ATP binding site, especially the � phosphate group, surrounding residues and water molecules. Based on DFT calculations, we proposed that ATP hydrolysis is initiated by the formation of Mg2þ mediated coordinate complex followed by the nucleophilic attack of a single water molecule (Water437) on the � -phosphate; the hydrolysis product ADP acts as a leaving group. The transition state structure was determined by an approximate saddle-point search. [doi:10.2320/matertrans.48.735]

Using accurate DFT calculations we have examined the role that Compound I of cytochrome P450 plays as a catalyst in the conversion of theophylline to 1-methylxanthine. This reaction proceeds in two steps according to the characteristics of the oxygen rebound mechanism. In this study we found that the activation energy for the transition state corresponding to the abstraction of the H atom at the C13 in theophylline is 9.3kcal/mol. This H atom abstraction is the rate-determining step in this reaction which takes place via a single electron transfer (SET) mechanism and leads to an intermediate containing theophylline cationic and iron-hydroxo species. The rebounding step between the reaction intermediate and the product alcohol complex is a barrierless step. The alcohol complex is then separated from the heme moiety and yields 1-methylxanthine by intramolecular rearrangement.

The mechanism of Cytochrome P450 3A4 mediated metabolism of (S)-N-[1-(3-morpholin-4ylphenyl)ethyl]-3-phenylacrylamide and its difluoro analogue have been investigated by density functional QM calculations aided with molecular mechanics/molecular dynamics simulations. In this article, we mainly focus on the metabolism of the morpholine ring of substrates 1 and 2. The reaction proceeds via a hydrogen atom abstraction from the morpholine ring by Compound I on a doublet potential energy surface. A transition state was observed at an

High temperature solid oxide cells (SOCs) are attractive for storage and regeneration of renewable energy by operating reversibly in solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) modes. However, the stability of SOCs, particularly the deterioration of the performance of oxygen electrodes in the SOEC operation mode, is the most critical issue in the development of high performance and durable SOCs. In this study, we investigate in detail the electrochemical activity and stability of La0.8Sr0.2MnO3 (LSM) oxygen electrodes in cyclic SOEC and SOFC modes. The results show that the deterioration of LSM oxygen electrodes caused by anodic polarization can be partially or completely recovered by subsequent cathodic polarization. Using in situ assembled LSM electrodes without pre-sintering, we demonstrate that the deteriorated LSM/YSZ interface can be repaired and regenerated by operating the cells under cathodic polarization conditions. This study for the first time establishes the foundation for the development of truly reversible and stable SOCs for hydrogen fuel production and electricity generation in cyclic SOEC and SOFC operation modes.

Focused ion beam-scanning electron microscopy (FIB-SEM) is a widely used and easily operational equipment for three-dimensional reconstruction with flexible analysis volume. It has been using successfully and increasingly in the field of solid oxide fuel cell. However, the phase contrast of the SEM images is indistinct in many cases, which will bring difficulties to the image processing. Herein, the phase contrast of a conventional Ni/yttria stabilized zirconia anode is tuned in an FIB-SEM with In-Lens secondary electron (SE) and backscattered electron detectors. Two accessories, tungsten probe and carbon nozzle, are inserted during the observation. The former has no influence on the contrast. When the carbon nozzle is inserted, best and distinct contrast can be obtained by In-Lens SE detector. This method is novel for contrast enhancement. Phase segmentation of the image can be automatically performed. The related mechanism for different images is discussed.

Decentralized energy systems are thought to have great potential for supplying electricity, cooling, and heating to buildings. A decentralized system combining a solid oxide fuel cell (SOFC) with an absorption chiller- heater (ACH) is proposed. The CO2-emissions and costs of using different configurations of this SOFC-based system to provide an office building in Tokyo with electricity, cooling and heating are calculated by using an SOFC- model and an absorption-chiller model together with data for cooling and heating loads measured at an office building in downtown Tokyo. The results are compared with the CO2-emissions and costs of a conventional system that obtains the base electricity requirements as well as electricity for an electric chiller–heater system from the central power grid. The fully decentralized SOFC-based energy system could result in a potential CO2 reduction of over 30% at an estimated cost increase of about 70% compared to the conventional system.

We present a theoretical study on the proton dissociation properties of the membranes for polymer electrolyte fuel cells. A density functional theory method is used to study the influence of fluorocarbon and hydrocarbon backbones on proton dissociation, the interaction of water molecules with the sulfonic acid group, and the energy barriers for proton dissociation. Better proton dissociation properties of CH(3)SO(3)H compared to CF(3)SO(3)H are observed from statistical analyses of the optimized structures for both systems. However, the calculated energy barriers for proton dissociation are lower for CF(3)SO(3)H than for the CH(3)SO(3)H system. At the same time, the interaction of water molecules is stronger for CH(3)SO(3)H than for CF(3)SO(3)H. Also, the analysis of the hydrogen-bonding network in both systems shows that the number of hydrogen bonds formed around the sulfonic acid group in CH(3)SO(3)H is larger than that in CF(3)SO(3)H. Therefore, the decrease of the energy barrier with increasing number of coordinating water molecules, pronounced in the case of CH(3)SO(3)H, may lower the barrier, which enhances good proton conductivity of a hydrocarbon-based polymer in low humidity conditions. Thus the hydration ability of a sulfonic acid group is an important factor for realizing better proton dissociation in low humidity conditions.

To study the atomistic behavior of the phosphoric ester molecule on the nascent Fe surface under boundary lubrication conditions, we adopted a hybrid tight-binding quantum chemical molecular dynamics method. First, we investigated chemical interactions between phosphoric ester and the nascent Fe surface. Phosphoric ester was shown to interact with the nascent Fe surface, forming both covalent and ionic bonds. Formation and dissociation dynamics of covalent bonds during tribochemical reaction was clearly observed during the simulation. The effect of friction condition on the tribochemical reaction dynamics was then studied, and it was indicated that friction would influence the formation and the dissociation of covalent bonds. By using a hybrid tight-binding quantum chemical molecular dynamics method, we obtained insights on initial tribochemical reaction processes for the formation of tribofilm from the phosphoric ester molecule on the nascent Fe surface.

Carr–Parrinello MD calculations for a simplistic periodic model of liquid water are performed to probe temperature dependence of infrared activation lifetime. IR activation is classically simulated by adding an appropriate velocity to the proton in a tagged water molecule. The evolution of hydrogen bonding descriptors is monitored through consecutive simulations to spot the onset of qualitative changes in the hydrogen bonding network; they are related to vibrational energy relaxation. The applied ionic simulation temperature (elevated by 20%) decreases the tendency to overbinding characteristic for CP MD calculations. Qualitatively estimated stretch lifetimes are 280, 320 and 400 fs for temperatures of 298, 320 and 370 K, respectively. This work gives direct evidence of the parallel dependence of both the decay of OH activation and the hydrogen bond network on temperature, which offers a viable explanation for the experimentally observable unusual increase in OH excitation lifetime with temperature.

We investigated the interactions of platinum metal clusters on the γ-alumina using a periodic density functional theory method. Results showed that electron transfer occurs between platinum metal clusters and γ-Al 2 O 3 . We also investigated NO adsorption properties (NO–Pt 4 /γ-Al 2 O 3 ) in order to clarify the support effect on NO activation in terms of the elongation of N–O bond length and NO molecular charge. In our results, the support increases NO activation for three-fold sites but decreases it for on-top and bridge sites. Moreover, the support changes the site preference of NO adsorption. In addition, in order to clarify the support effect at finite temperature, we studied the dynamic behaviors of supported precious metal catalysts by using a tight-binding quantum chemical molecular dynamics program named ‘Colors’.

In this study, we performed periodic DFT calculations to clarify the interfacial properties of zirconia-supported precious metal catalyst systems. Atomic precious metals (Pt, Pd and Rh) and four-metal-atom clusters (Pt4, Pd4 and Rh4) were deposited on the ZrO2(1 1 1) surface. The Pt and Rh show much stronger interaction with the ZrO2(1 1 1) surface than the Pd, indicating that the Pt–ZrO2 and Rh–ZrO2 interfaces are energetically more stable than the corresponding Pd–ZrO2 interface. The effect of support relaxation on the adsorption energies reveals that a larger support relaxation effect can be observed on the Pt–ZrO2 interface compared to the Pd–ZrO2 interface. The Pt adsorption was associated with the largest support rearrangement with strong Pt–Zr interaction. The precious metal atoms on the ZrO2(1 1 1) surface were positively charged. The electron transferred from the precious metal to the ZrO2(1 1 1) surface was localized on the Zr atom. Moreover, electron exchanges on the Pt–ZrO2 and Rh–ZrO2 interfaces were more significant than that on the Pd–ZrO2 interface. Additionally, the oxidization effects on the interaction between the precious metals and the ZrO2 support were also investigated. The oxidization weakened the metal–metal interaction of the M4 cluster, while the metal–ZrO2 interaction was increased by the oxidization.

The precise control of the thickness of amorphous layers and concentration of dopant atoms in thin layers is important for the fabrication of ultrashallow highly doped junctions. It was reported that amorphous layers suppress the channeling tail of implanted boron atoms. In this work, we studied the dynamics of boron implantation into a silicon substrate preamorphized by Ge irradiation, using our novel hybrid tight-binding quantum chemical molecular dynamics method. We have implemented a dynamic hybridization method in our study of preamorphization and implantation, in which a focused atom changes its position with simulation time. In the developed dynamic hybridization method, the region treated by the quantum chemistry method can dynamically change with simulation time. We have successfully applied the developed method and observed that the decrease in the kinetic energy of the implanted boron atom is correlated with the formation of chemical bonds between the implanted boron atom and the surrounding silicon atoms.

In the development of materials for nano-scale devices, particularly those including impurities, defects, surfaces, and hetero-interfaces, estimation of their electrical conductivity based on quantum chemistry provides important information. Existing quantum mechanics-based methods for theoretically estimating the electrical conductivity require huge computational cost, which prohibit their applications to complex systems. We have already succeeded in the development of our original tight-binding quantum chemical molecular dynamics program "Colors", which realizes a calculation speed over 5000 times faster than the conventional first principles molecular dynamics methods. Here we present a novel electrical conductivity estimation method based on "Colors" combined with Monte Carlo algorithm for estimating the value corresponding to the carrier mobility. We have applied the developed method to systems of C, Si, Ge, and Sn. Calculated results quantitatively agree with experimental data, which indicates the validity of the developed method. We have also applied the developed method to the study of Si surface.

The charge transfer and structural distortions that occurred in the complexes cuprous(I) bis-phenanthroline (Cu(NN)2+) (NN denotes 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline and 2,9-di(trifluoromethyl)-1,10-phenanthroline) upon excitation with an irradiation of light were studied by density functional theory (DFT). The calculations showed that the electrons transferred from central metal Cu to ligands with the transition of the complexes Cu(NN)2+ from ground state to excited state. As a consequence, the central copper in the excited state of Cu(NN)2+ exhibited similar electronic density to that in the corresponding complex Cu(NN)22+. Accompanying with this transfer process, the coordination polyhedra of Cu(NN)2+ became distorted upon excitation. The structural distortion was significantly reduced by increasing the steric bulk of the 2- and 9-positions substituents in the ligands NN, which is helpful for the increase of the life time of the excited state.

CO adsorption over Pd 4 and Pt 4 cluster supported by c-ZrO 2 (1 1 1) and CeO 2 (1 1 1) catalyst systems was investigated using periodic density functional method in order to clarify the support effect on CO activation. We found that the support increases the CO activation for bridge and three-fold sites but decreases for the atop site. Moreover, it was found that the support changes the site preference for the CO adsorption. Bridge site on both the Pt 4 /c-ZrO 2 and Pt 4 /CeO 2 show larger CO adsorption energies than those on the other sites while the atop site is energetically preferable on isolated Pt 4 cluster. c-ZrO 2 supported Pd shows the largest CO activation with large charge transfer from the catalyst to the CO molecule. This reveals that ZrO 2 supported Pd can be a good catalyst for CO activation because of its higher probability to the three-fold site CO adsorption. We also found that positively charged M 4 clusters on the support keep their strong electron-donating properties and have enough charge density to contribute to the activation of an adsorbed CO molecule by a charge transfer.

Using quantum chemical modelling we describe a novel effect in the mechanism of CYP3A4 metabolism for the arene substrate with o-substituent yielding a lone pair donation to conjugate π system; this will compensate for the loss of aromaticity on formation of the tetrahedral complex and lower the rate-determining energy barrier.

This work reported the investigation of the structural distortions and charge-transfer processes that occurred in the complex of cuprous(I) bis-2,9-dimethyl-1,10-phenanthroline ( Cu ( dmp ) 2 + ) upon oxidation to copper(II), Cu ( dmp ) 2 2 + , through a excited state of Cu ( dmp ) 2 + by density functional theory. The intramolecular electronic transfer from central metal-to-ligand (MLCT) upon the irradiation of light energy is confirmed. Due to this MLCT excitation, the structure of the excited state of Cu ( dmp ) 2 + is distorted and reorganized to adapt with the change of charge in central metal. As a result, the excited state of Cu ( dmp ) 2 + is formed, which has the similar electronic and structural properties with Cu ( dmp ) 2 2 + . The bulky substituents in 2- and 9-positions of the phenanthroline ligands can restrain the structural distort and decrease nonradiative decay rate. Thus, the electronic and steric effects of the ligands in the cuprous photo-sensitive complexes have important consequences in the behavior of their excited state.

The adsorption energies of NH 3 at different positions in acidic mordenite, viz., main channel, side pocket, and double four-membered rings, are investigated using periodic density functional theory method. Furthermore, for the first time, the dynamic behavior of NH 3 interacting with Bronsted acid site in the main channel has been monitored. The results reveal that the adsorption energies of ammonia on Bronsted acid sites in the main channel (T 4 , T 2 , and T 1 ) are higher than that in the side pocket (T 3 ). Consequently, the strength of Bronsted acid sites follows the same order. Ammonia dynamics results show that the protons are in continuous transfer, where NH 3 acts as a bridge for transferring protons in between ammonium ion and framework oxygen ions.

A system-based approach is effective in conducting simulation modeling of complex chemical systems. However, traditional centralized or monolithic modeling approaches are restricted to the knowledge domain of the modeler, and therefore these approaches cannot lead to the discovery of potentially important knowledge from other areas. Furthermore, knowledge of important phenomena, which are unfamiliar to the researcher who is designing the chemical system but may be well-known in other domains, are often overlooked in the conventional modeling process, leading to incorrect predictions of the modeled chemical system characteristics. An emergent simulation modeling approach for knowledge discovery (emergent simulation approach) is proposed to evaluate phenomenological behavior in chemical systems. In this emergent simulation approach, knowledge experts who have developed computational models that simulate the phenomena occurring under different design and operation conditions make those models available to a software system. Other engineers and scientists can access the software system to search for models simulating phenomena that match certain conditions and specifications describing a particular chemical system. In order to support the search and match process, an ontological markup language for chemical systems is proposed. Researchers can use this markup language to create a specification of the chemical system that they are investigating. That specification is used to discover which computational models can simulate phenomena that could occur in the given specification. This paper presents 1) the concept of the emergent simulation approach, 2) an ontological markup language developed for the emergent simulation of phenomena in chemical systems, and 3) a design for a software system that supports the proposed emergent simulation approach.

Recently, we have developed a new tight-binding quantum chemical molecular dynamics program “Colors” for combinatorial computational chemistry approach. This methodology is based on our original tight-binding approximation and realized over 5000 times acceleration compared to the conventional first-principles molecular dynamics method. In the present study, we applied our new program to the simulations on various realistic large-scale models of the automotive three-way catalysts, ultrafine Pt particle/CeO2(111) support. Significant electron transfer from the Pt particle to the CeO2(111) surface was observed and it was found to strongly depend on the size of the Pt particle. Furthermore, our simulation results suggest that the reduction of the Ce atom due to the electron transfer from the Pt particle to the CeO2 surface is a main reason for the strong interaction of the Pt particle and CeO2(111) support.

Understanding pharmacokinetics in the human body is of the utmost relevance in various stages of medical services. However, a problem arises when conveying pharmacokinetic knowledge to people unfamiliar with the discipline. To overcome this communication barrier between different disciplines, we implemented pharmacokinetic expertise as a computational simulator with a graphical user interface, which is intended to assist instinctive understanding of pharmacokinetics. The developed simulator will help non-experts such as medical personnel, patients, and medicinal chemists to understand and use pharmacokinetics in a rational way.

Summary New advances in Internet technologies and computer modeling provide opportunities for collaborative systems to support research and development in the field of industrial ecology. In particular, new information technologies such as semantic search engines based on ontologies could help researchers to link fragments of knowledge generated at research centers from around the world. Using a storyline of four imaginary researchers who hope to find collaborators in order to develop their research findings, we illustrate two levels of a four-level architecture for an Internet-based knowledge integration and collaboration environment for integrated environmental assessment. The foundation of the proposed architecture is a belief that computational models are an effective medium for conveying expert knowledge of various phenomena. Drawing from this premise, the first level of the architecture stands on a base of computational models that in some way represent the expert knowledge of the model builder. At the second level, we provide markup and interface definition tools to describe the type of knowledge contained in each model, together with the types of information services that can be provided. The results of research at these two levels of an Internet-based knowledge integration environment for integrated environmental assessment in industrial ecology are presented in this article. Our work on the third level of model searching and matching and the fourth level of parametric model integration and solving will be presented in subsequent articles.

Different types of cationic species acting as Lewis acid sites as well as Na-counter ion in dealuminated zeolites are investigated, for the first time, using periodic density functional method. The energy of ammonia adsorption is taken as a measure for the acidity. The results reveal that the relative strength of the investigated active sites increases in the order: Na+ Si+. Moreover, the interaction of NH3 with tri-coordinated aluminum dislodged in the framework is less favorable than that with the neighboring silicon ion.

A novel kinetic Monte Carlo simulator “ARC” was developed to investigate hydrogen diffusion process in metals and alloys. The results of the hydrogen diffusion coefficients in palladium, silver, and Pd 1− x Ag x ( x ≤ 0.5) are in excellent agreement with experimental results. Two different diffusion sites, Pd-rich diffusion site and Ag-rich diffusion site, are found to be necessary to explain diffusion behaviors of hydrogen in palladium–silver alloys. Detailed analysis clarified that hydrogen atoms preferentially diffuse through the palladium-rich region of palladium–silver alloys at low silver concentrations, and that the hydrogen diffusion process at low silver contents is dominated by the jumps in palladium-rich regions. The migration barrier of hydrogen from Pd-rich diffusion site to Ag-rich diffusion site is estimated to be between 0.40 and 0.45 eV.

The clarification of the excited states dynamics on TiO 2 surface is important subject for the design of the highly active photocatalysts. In the present study, we applied our novel tight-binding quantum chemical molecular dynamics method to the investigation on the photocatalytic oxidation dynamics of acetone by photogenerated OH radicals on the hydrated anatase TiO 2 surface. The elucidated photocatalytic reaction mechanism strongly supports the previous experimental proposal and finally the effectiveness of our new approach for the clarification of the photocatalytic reaction dynamics employing the large simulation model was confirmed.

Improvement of anode characteristics of solid oxide fuel cells is important for the better cell performance and especially the direct use of hydrocarbons. A mixture of ceramics and metal is generally used as anode, and different combinations of ceramics and metals lead to different electrode characteristics. We performed large-scale calculations to investigate the characteristics of Ni/CeO2 and Cu/CeO2 anodes at the electronic level using our tight-binding quantum chemical molecular dynamics program. Charge distribution analysis clarified the electron transfer from metal to oxide in both anodes. The calculations of density of states clarified different contributions of Ni and Cu orbitals to the energy levels at around Fermi level in each cermet. Based on the obtained results, we made considerations to explain different characteristics of both cermet anodes. The effectiveness of our approach for the investigation of complex cermet system was proved.

Ionic properties at the solid–aqueous solution interface are investigated to monitor their effects on the hydration behavior and adsorption mechanisms on a MgO(001) surface by means of computational chemistry methods using density functional theory and molecular dynamics calculations. Especially, the dynamic behavior and dissociative adsorption of water molecules on the MgO(001) surface in the aqueous solution were successfully simulated. The results revealed that the ionic properties, such as electronegativity and ionic sizes, play an important role on their hydration behavior and interaction with oxide surfaces. Especially, MgO surface was found to undergo the hydroxylation due to the dissociated H + and OH − ions.

Our tight-binding quantum chemical molecular dynamics method was applied to the investigations on the mechano-chemical reaction dynamics during the chemical–mechanical polishing (CMP) process of SiO 2 surface by CeO 2 particle. The mechanical forces introduced by the CeO 2 particle were found to accelerate the chemical reactions at the CeO 2 –SiO 2 interface. The time profile of the bond population and atomic charges reveals the mechanism of the mechano-chemical reaction dynamics during the CMP process. The electronic states change from Ce 4+ to Ce 3+ was observed during the CMP process and this reduction reaction is related to the specific characteristics of the Ce element, which has two oxidation states, Ce 3+ and Ce 4+ . Finally, we concluded that our tight-binding quantum chemical molecular dynamics method is an effective tool to clarify the mechano-chemical reaction dynamics during the CMP process, because these investigations cannot be realized by the conventional first-principles calculation and classical molecular dynamics method.

Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulphonate) (PSS) has been widely used in light-emitting devices as hole transport layer and in photovoltaic devices as hole-collecting layer. In the present study, various quantum chemical calculations were carried out for the investigation of low-lying excited states of ethylenedioxythiophene (EDOT), and styrenesulphonic acid. The lowest adiabatic transition energies were calculated using configuration interaction singles method. The time-dependent density functional theory was also applied for the calculation of the vertical excitation energies. Differential self-consistent-field-based density functional theory method is well known to show good performance for the geometry of excited state and hence it was also applied to study of the first singlet excited state. In addition to the calculation of the monomer, the electronic properties of PEDOT were calculated by periodic density functional theory method and the result is in good agreement with the experimental observation.

Periodic density functional and tight-binding quantum chemical molecular dynamics calculations were employed to clarify the characteristics and dynamics of surface hydroxyl groups on Pt/ZrO 2 catalysts. We applied the periodic density functional theory calculations to the investigations on the effect of hydroxyl groups on the adsorption characteristics of Pt atom on ZrO 2 (111) support and hydroxyl groups were found to decrease the adsorption energy of Pt atom on the ZrO 2 (111) support. Furthermore, we applied our original tight-binding quantum chemical molecular dynamics method to the clarification of the dynamic behaviors of the hydroxyl group on the Pt/ZrO 2 (111) and ZrO 2 (111) surface. We found that the Pt atom triggers the migration and hopping of the H atom of the hydroxyl group. The migration of H atoms on the Pt/ZrO 2 catalyst was discussed in the sight of their catalytic activity.

The precise control of dopant atom is one of the most important challenges to fabricate ultra-shallow and highly doped junctions. In the present study, the activation process of B atom in Si crystal was investigated at low temperature of 500 °C by using our tight-binding quantum chemical molecular dynamics method, which is over 5000 times faster than the conventional first-principles molecular dynamics method. The simulation results indicate that the B atom diffuses through the interstitial sites in the Si crystal even at low temperature of 500 °C. Moreover, we found that the boron atom tends to migrate into the lattice vacancy and however the diffusion of the B atom is very hard after the boron atom is trapped in the single lattice vacancy. On the other hand, when there are two adjacent lattice vacancies in the Si crystal, the B atom migrates frequently between two adjacent vacancies back and forth. This result predicts that two adjacent lattice vacancies impede the B activation in the Si crystal. Finally, we confirmed that our tight-binding quantum chemical molecular dynamics program is very effective to elucidate the boron activation process in the Si crystal, considering the electronic states and electron transfer dynamics.

Density functional theory calculations were applied to investigate the β-hydrogen-elimination of the ethyl-palladium complexes, cis-(Me3P)2(Et)PdHX, where X = Cl, Br or I, to form ethene and hydrido-palladium complexes. Effects of substitution of halogen ligands and coordination of solvent molecules on geometric parameters and energies were investigated. Studies on solvated reaction intermediates revealed the agostic ethyl-palladium complexes to be important in the decomposition processes of the ethyl-palladium complexes.

This work reported an investigation on the excited state and electronic transfer excitation of cuprous (I) bis-phenanthrouline complex by density functional theory. The intramolecular charge transfer from central metal to ligand (MLCT) during the excitation was observed. The transfer direction and degree were discussed on the basis of analyzing the Mulliken charge. The structural distortion caused by the charge transfer in the excited state was confirmed. The excited state was found having the characters similar with Cu(II) complex both in electronic and geometrical properties. The large structural distortion found between ground state and excited state could lead to a decrease in the lifetime of excited state as well as a non-radiative decay. The excitation energies and oscillator strengths of cuprous (I) bis-phenanthrouline were derived using time-dependent density functional method. The values of excitation energies are good agreement with the results of the experimental measuring.

A simulation framework for flexible evaluation of various distributed building energy systems based on the integration of component device simulation models is presented. Device technology models were constructed for a solid oxide fuel cell (SOFC), a gas turbine, a double pipe heat exchanger, and a compressor. A scheme is proposed for defining model interfaces in order to improve the flexibility and accessibility of the models. Based on that scheme, interfaces are defined for each device model. The component device models are integrated to construct system models of (1) a hybrid system combining an SOFC and a gas turbine (SOFC/GT system) and (2) a stand-alone SOFC system. The integrated model of the SOFC/GT system is then used to carry out a multi-objective optimization in order to study the tradeoffs between cost and CO2 emissions of the SOFC system operation for a given electricity demand. Through these analyses, the optimal configuration of the SOFC/GT system and the optimal operation conditions of the SOFC system for the given electricity demand were explored. Copyright © 2005 John Wiley & Sons, Ltd.

This paper presents a modularized simulation modelling framework for evaluating the impacts on economic cost and CO2 emissions resulting from the introduction of a solid oxide fuel cell (SOFC) system into the existing mix of centralized power generation technologies in Japan. The framework is comprised of three parts: a dual-objective linear programming model that solves the generation best-mix problem for the existing power generation technologies; a nonlinear SOFC system model in which the economic cost and CO2 emissions by the SOFC system can be calculated; and the Queuing Multi-Objective Optimizer (QMOO), a multi-objective evolutionary algorithm (MOEA) developed at the EPFL in Switzerland as the overall optimizer of the combined power supply system. Thus, the framework integrates an evolutionary algorithm that is more suitable for handling nonlinearities with a calculus-based method that is more efficient in solving linear programming problems. Simulation experiments show that the framework is successful in solving the stated problem. Moreover, the three components of the modularized framework can be interconnected through a platform-independent model integration environment. As a result, the framework is flexible and scalable, and can potentially be modified and/or integrated with other models to study more complex problems. Copyright © 2004 John Wiley & Sons, Ltd.

The relative strength of Bronsted acid sites in isomorphously substituted chabazite (M–CHA; Me=Al3+, Ga3+, B3+, Sc3+ and Fe3+) and aluminophosphate-34 (MAlPO-34; Me=Ti4+, Si4+, Cr2+, Mn2+, Fe2+, Co2+ and Ni2+) have been investigated using periodic density functional theory. Adsorption energy of NH3 and deprotonation energy are considered for measuring the acidity. It has been found that Al3+–CHA and Mn2+–AlPO-34 possess the strongest acidic character. Moreover, a correlation between deprotonation energy and adsorption energy of NH3 has been observed.

In this paper, strategies to successfully introduce solid oxide fuel cells (SOFCs) into industry and society are discussed using a scenario approach. Scenarios for Japanese energy systems are developed to portray the situation up to the year 2050, in order to consider the potential interrelation of SOFCs with other power generation technologies, and to direct further investigation and stimulate discussion among researchers and stakeholders. Scenarios are constructed by combining a number of scenario options, such as technical, social, political and economic aspects. Specific attention is focused on the lifecycle of SOFCs. A power generation planning model developed in a previous study was extended to model decision-making for power generation capacity planning based on cost minimization, subject to other constraints and requirements over the focal time period of 2001–2050. In this way, it is possible to assess for each scenario not only the feasible introduction rate of SOFCs, but also the CO2 emissions, cost, and energy security requirements for the entire energy system, including both distributed and centralized power systems. The results of the analyses elucidate the effectiveness of different technical and political alternatives, such as technological breakthrough, recycling, security of materials and production facilities, on the successful introduction of SOFCs in Japanese power systems.

A new methodology “Combinatorial Computational Chemistry” was proposed to realize theoretical high-throughput screening of materials. In this review, we introduced our recent successful applications of combinatorial computational chemistry to material design. Especially, we succeeded in the development of huge number of new simulation programs for combinatorial computational chemistry. For example, our SCF-tight-binding quantum chemical molecular dynamics program is very effective to realize high-throughput screening, since it realizes more than 5,000 times acceleration. Furthermore, we succeeded in the development of multi-physics quantum chemical molecular dynamics program based on our SCF-tight-binding theory, which can simulate multi-physics phenomena including chemical reaction, shear, impact, stress, flow, electric field and so on. This new program realizes various process design in addition to material design on the basis of the combinatorial computational chemistry. We emphasized here that our new simulation programs are very powerful tool to realize high-throughput screening for both material and process design, which cannot be accomplished by the traditional first-principles approach.

New power generation technologies are expected to reduce various environmental impacts of providing electricity to urban regions for some investment cost. Determining which power generation technologies are most suitable for meeting the demand of a particular region requires analysis of tradeoffs between costs and environmental impacts. Models simulating different power generation technologies can help quantify these tradeoffs. An Internet-based modelling infrastructure called DOME (distributed object-based modelling environment) provides a flexible mechanism to create integrated models from independent simulation models for different power generation technologies. As new technologies appear, corresponding simulation models can readily be added to the integrated model. DOME was used to combine a simulation model for hybrid SOFC (solid oxide fuel cell) and gas turbine system with a power generation capacity and dispatch optimization model. The integrated models were used to evaluate the effectiveness of the system as a centralized power source for meeting the power demand in Japan. Evaluation results indicate that a hybrid system using micro-tube SOFC may reduce CO2 emissions from power generation in Japan by about 50%. Copyright © 2004 John Wiley & Sons, Ltd.

A simulation model for a tubular solid oxide fuel cell (SOFC) was developed by the object-based approach to calculate the current distribution, gas concentration distribution, and temperature distribution at the steady states and transient operation states. The transient electrical and temperature response to a load change was simulated for the both cells with the diameter of 22 mm (standard cell) and the diameter of 2.4 mm (micro-tube cell). The time required to reach the new steady state as the operating voltage was changed from 0.7 to 0.5 V for the micro-tube cell was found to be 15 s, which is much shorter than that of the standard cell.

A scheme for a collaboration platform for the research and development of solid oxide fuel cell (SOFC) systems is proposed. The proposed platform enables users to design introduction scenarios of the SOFC system into the society and promotes interdisciplinary collaborations among SOFC researchers and developers by providing functions for 1) evaluating the environmental impacts of the SOFC system and its manufacturing process; 2) estimating changes in infrastructures, commodity flows among industries, and the social system; 3) failure prevention based on predictive analysis. The systematic structure and basic mechanisms to realize each type of functionality for the holistic design of SOFC systems and the introduction scenarios are described.

A system is proposed to predict and prevent failures that could potentially occur in solid oxide fuel cell (SOFC) systems. The system elucidates the causal chain of a failure mechanism and suggests changes in design specifications to the designer by using the abstracted knowledge on failure mechanisms in specific fields of SOFC design and other fields of technology design. The basic concepts and mechanisms for accumulation of knowledge on failure mechanisms and prediction of the failures are described. A demonstration of a prototype failure prediction and prevention system developed for SOFC design is presented.

Electrode processes in solid oxide fuel cells are intensively studied to increase the system efficiency to compete with that of the state-of-the-art LNG-fueled combined cycle thermal power plant. Because the electrode performance depends both on electrode materials and microstructure, we are obliged to breakdown the complexity of phenomena in the porous electrode into elementary processes by best utilizing both the advanced measurement and the simulation techniques. Closely examining the efforts in literature [1-7], we have taken the combined top-down and bottom-up approach. The most difficult issue has lied on the meso-scale modeling, which typically is based on microkinetic modeling [5-8]. To guarantee the predictivity of the modeling, it is inevitable to realize the simulation without arbitrary fitting parameters that are not necessarily based on realistic physics. For this purpose, we first exhaustively summarized literature data followed by the careful examinations. Next, we have made exhaustive simulations assuming different combinations of parameters in literature. Finally, we obtained a set of parameters that matches with experimental observations within reasonable differences. The details together with the results of top-down and bottom up simulations will be introduced together with future perspectives. Acknowledgements The activities of INAMORI Frontier Research Center is supported by Kyocera Co. Ltd. The activities of Advanced Automotive Research Collaborative Laboratory in Hiroshima University are supported by Mazda Corporation. The part of the research is supported by CREST, Japan Science and Technology Agency. References [1] J. Mizusaki, H. Tagawa, T. Saito, T. Yamamura, K. Kamitani, K. Hirano, S. Ehara, T. Takagi, T. Hikita, M. Ippommatsu, S. Nakagawa, K. Hashimoto, Solid State Ionics, 70/71, 52 (1994) [2] W. Yao and E. Croiset, Can. J. Chem. Eng., 93, 2157 (2015) [3] A. Bieberle, L. P. Meier, L. J. Gauckler, J. Electrochem. Soc., 148, A646 (2001) [4] A. Utz, H. Störmer, A. Leonide, A. Weber, E. Ivers-Tiffée, J. Electrochem. Soc., 157 B920 (2010) [5] W. G. Bessler, S. Gewies, M. Vogler, Electrochim. Acta, 53, 1782 (2007) [6] W. G. Bessler, Solid State Ionics, 176, 997 (2005) [7] M. Vogler, A. Bieberle-Hütter, L. Gauckler, J. Warnatz, and W. G. Bessler, J. Electrochem. Soc., 156, B663 (2009) [8] H. Kohno, S. Liu, T. Ogura, T. Ishimoto, D. S. Monder, K. Karan, M. Koyama, ECS Trans., 57(1), 2821 (2013)

Electrode kinetics in solid oxide fuel cells are intensively studied to realize the highly efficient system in small- and large-scale applications. As the understandings become deeper, it is important to understand the atomistic-level kinetics of the electrode catalysis as well as to understand the essential nature of catalyst properties. Thus the application of computational chemistry to this issue will be an effective and important option. The author’s research group has theoretically investigated the oxygen reduction reaction kinetics over La1-xSrxCoO3-δ cathode by using density functional theory method and the Ni-YSZ anode by using both density functional theory method [2] and a microkinetic simulation [3] State-of-the-art results will be introduced in the presentation. Acknowledgements Activities of INAMORI Frontier Research Center is supported by Kyocera Co. Ltd. The part of the research is supported by CREST, Japan Science and Technology Agency. References [1] T. Ishimoto, K. Sato, T. Tada, K. Amezawa, M. Koyama, ECS Trans., 68(1) (2015) 651. [2]S.-x. Liu, T. Ishimoto, D. Monder, M. Koyama, J. Phys. Chem. C, 119 (2015) 27603-27608. [3] H. Kohno, S. Liu, T. Ogura, T. Ishimoto, D. S. Monder, K. Karan, M. Koyama, ECS Trans., 57(1) (2013) 2821-2830.