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[Display omitted] • Polarizability and Raman intensity of the simplest quinoid hydrocarbon BQM. • SVD analyses for orbital deformations by the electric field and molecular vibrations. • NPOs give an unique orbital representation for electronic deformations in the field. • Large long-axis polarizability and Raman intensity due to HOMO-LUMO promotion. • Mechanism of the weak Raman intensity of the breathing-like CCC stretch mode. The polarizability and Raman intensity of the smallest quinoid hydrocarbon p -benzoquinodimethane were analyzed as electronic deformations in the electric field. The perturbed canonical MOs (CMOs) were transformed to NPOs using the singular value decomposition. The NPOs can represent the intrinsic characters of the electronic deformations that CMOs cannot describe properly. The electronic deformations of HOMO-LUMO type dominate the long-axis polarizability and the strongest Raman intensities. TDDFT calculations demonstrated the relevance of the NPOs to the singly-excited wavefunctions of excited states. The mode-specific predictivity of Raman intensity was discussed based on the polarizability components obtained by B3LYP and CCSD(T) calculations. [ABSTRACT FROM AUTHOR]

Left: The p (dark-blue), p′ (light-blue) and q (dark-magenta, q′ (light-magenta) paths at the MP2/cc-pVTZ theory level. The { p , p′ } and { q , q′ } path-packets define the least and most preferred directions of charge density accumulation. The undecorated red and green spheres correspond to the ring critical points (RCP s) and bond critical points (BCP s) respectively. Right: The corresponding stress tensor { p σ , p′ σ } and { q σ , q′ σ } path-packets with a ×10 magnification factor applied. • Complete 3-D, non-minimal, directional bonding for the [1.1.1]propellane molecule. • Debated [1.1.1]propellane axial bond determined to be a weak, charge-shift bond. • Quantified chemical influence of the axial bond on the neighboring bonding. • Consistency of the main results found at the MP2, CCSD and B3LYP theory levels. • Stress tensor results consistent with presence of an axial charge-shift bond. We investigated the [1.1.1]propellane molecule using the 3-D bond-path framework set B and the stress tensor B σ within the quantum theory of atoms in molecules (QTAIM). The controversial axial bond was determined to be a charge-shift bond comprising significant bond metallicity that correlated with values of the bond stiffness S < 1. The influence of the axial bond on the neighboring bonding is quantified in terms of unexpectedly low bond stiffness S values and a new measure of charge-shift bonding, the polarizability P. Consistency of these results was found at the MP2, CCSD and B3LYP theory levels. [ABSTRACT FROM AUTHOR]

The linear and nonlinear properties of isomeric forms of pyridinium-N-phenoxide betaine dye were investigated in protic and aprotic solvents using atomistic simulations. We employed the sequential Quantum Mechanics/Molecular Mechanics (S-QM/MM) and the free energy gradient (FEG) methods to optimize the geometry of each isomer in chloroform, acetonitrile, methanol and water. The results show a complex dependence of the first hyperpolarizability with respect to the solvent nature and isomeric form, with a marked effect of conformational changes for para-betaine. Large contrasts of the first hyperpolarizability show a clear distinction between isomeric forms in solution that could be experimentally detected. [ABSTRACT FROM AUTHOR]

The effect of rotational isomerism on the values of first hyperpolarizability is studied by the example of two chromophores 7-DMA-VQV-TCP and 3-DMA-VQ on V-TCP with quinoxaline and quinoxalinone moieties in the π-electron bridge. At the isomers formation the rotations about three single bonds are considered, thus providing eight possible conformers for each chromophore. The analysis of the results of DFT calculations demonstrates the presence of one lowest-energy conformer characterized by dominating probability for each chromophore. The calculations show that for both chromophores all rotational isomers are characterized by the first hyperpolarizability values rather close (within 8% and 11%) to statistically averaged ones. [ABSTRACT FROM AUTHOR]

The PES and velocity-map images of the linear anions AgC 2n H− (n =1,2) are shown here. [Display omitted] • The PES of anionic AgC 2 H and AgC 4 H were obtained. • The electronic configuration of the anions was confirmed. • Bond order and character of Ag-C bond in the neutral species were analyzed. The electronic structures of AgC 2n H− (n = 1, 2) are reported by using photoelectron imaging and ab initio calculations. The results indicate that all the ground states of anion and neutral AgC 2n H have a linear geometry. The electron affinities (EAs) are measured to be 1.123 and 1.379 eV for AgC 2 H and AgC 4 H, respectively. The NRT analysis shows that ionic character dominates the Ag–C chemical bond in these neutral species. The calculated static dipole polarizability (α) and second hyperpolarizability (γ) of the molecules indicate that the cap of Ag could enhance the nonlinear optical responses. [ABSTRACT FROM AUTHOR]

Coupled-cluster calculations of static electronic dipole polarizabilities for 145 organic molecules are performed to create a reference data set. The molecules are composed from carbon, hydrogen, nitrogen, oxygen, fluorine, sulfur, chlorine, and bromine atoms. They range in size from triatomics to 14 atoms. The Hartree–Fock and 2nd-order Møller–Plesset methods and 34 density functionals, including local functionals, global hybrid functionals, and range-separated functionals of the long-range-corrected and screened-exchange varieties, are tested against this data set. On the basis of the test results, detailed recommendations are made for selecting density functionals for polarizability computations on relatively small organic molecules. [ABSTRACT FROM AUTHOR]

We present an implementation of the partitioning of the molecular polarizability tensor (Krishtal et al. (2006) [15]) that explicitly employs the first-order electronic density from linear-response coupled-perturbed Kohn-Sham calculations. This new implementation provides a simple and robust tool to perform the partitioning analysis of the calculated electrostatic polarizability tensor at negligible additional computational effort. Comparison with numerical results for Si3 and Na20, and test calculations in all-trans-polyacetylene oligomeric chains up to 250Å long show the potential of this methodology to analyze the response of large molecules and clusters to electric fields. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three helical complexes are designed to study structure–properties relationship. [•] The Na atom possesses an appropriate size to fit in the helical cavities. [•] The Py–pym–2Na has the smallest interaction energy. [•] The α 0 values improve with increasing the atomic number. [•] The Py–pym–2Na has the largest β 0 value among three helical complexes. [Copyright &y& Elsevier]

Highlights: [•] Molecular polarizabilities, α P, of methyl branched alkanes measured using THz-TDS. [•] Branched methyl group contribution independent of chain length or branch position. [•] Results compared with DFT–PCM and a simple bond additive model. [•] Only DFT–PCM accurately reproduces α P if dispersion corrections are included. [•] Empirical group additive method still effective for describing their α P at 1THz. [Copyright &y& Elsevier]

[Display omitted] • The gas-IL interactions are calculated using different quantum chemical methods. • The cation–anion interaction cannot be used to predict the FFV for multivalent ILs. • The interaction of gases with IL ions is related to the ESP maxima and minima. • The interaction between gases with one IL molecule is related to the IL volumes. Solute-solvent interactions are often evaluated to understand and explain gas solubilities. This information is regularly used to interpret gas solubility and separation within ionic liquids (ILs). Here, we use several different quantum chemical and previous molecular dynamics simulation results to show that strong solute–solvent interactions neither lead to high solubility nor to high selectivity, with respect to other solutes. Instead, the solute–solvent interaction strength with different isolated IL ions is affected by the electrostatic extremes. Also, the solute–solvent interaction with different IL molecules is strongly correlated to the molecular volumes or polarizabilities (within a series of same-anion based ILs). [ABSTRACT FROM AUTHOR]

[Display omitted] • Electronic properties of ZnO nanoclusters computed using damped and pulsed response. • Damped and pulsed response results asymptotically converge. • Pulsed response offers the opportunities in studies of light-matter interactions. Motivated by the interest in zinc oxide nanostructures and their properties, we calculate in this work molecular polarizabilities and hyperpolarizabilities of a series of zinc oxide nanoclusters using modern response theory in the form of damped and pulsed response for both Hartree-Fock and DFT reference states. We show that as the size of the cluster grows, both real and imaginary parts of polarizability, computed with these two distinct approaches, asymptotically converge. We also show the importance of eliminating the dangling bonds in small clusters for predicting the correct trend in the values of the HOMO/LUMO gap. Finally, we calculate the hyperpolarizability tensors, associated with the second order nonlinear optical effects, in the hexagonal (wurtzite) phase of ZnO nanoclusters and demonstrate a highly nonlinear growth of this quantity with the cluster size. [ABSTRACT FROM AUTHOR]