Validation of a model for the interaction-induced long-range first hyperpolarizability

Partitioning of interaction-induced nonlinear optical properties of molecular complexes. I. Hydrogen-bonded systems

Interaction-induced electronic and vibrational (hyper)polarizabilities were decomposed into different interaction types (electrostatic, exchange, induction and dispersion).

On the physical origins of interaction-induced vibrational (hyper)polarizabilities

This paper presents the results of a pioneering exploration of the physical origins of vibrational contributions to the interaction-induced electric properties of molecular complexes. In order to analyze the excess nuclear relaxation (hyper)polarizabilities, a new scheme was proposed which relies on the computationally efficient Bishop-Hasan-Kirtman method for determining the nuclear relaxation contributions to electric properties. The extension presented herein is general and can be used with any interaction-energy partitioning method. As an example, in this study we employed the variational-perturbational interaction-energy decomposition scheme (at the MP2/aug-cc-pVQZ level) and the extended transition state method by employing three exchange-correlation functionals (BLYP, LC-BLYP, and LC-BLYP-dDsC) to study the excess properties of the HCN dimer. It was observed that the first-order electrostatic contribution to the excess nuclear relaxation polarizability cancels with the negative exchange repulsion term out to a large extent, resulting in a positive value of Δα(nr) due to the contributions from the delocalization and the dispersion terms. In the case of the excess nuclear relaxation first hyperpolarizability, the pattern of interaction contributions is very similar to that for Δα(nr), both in terms of their sign as well as relative magnitude. Finally, our results show that the LC-BLYP and LC-BLYP-dDsC functionals, which yield smaller values of the orbital relaxation term than BLYP, are more successful in predicting excess properties.

INTERACTION OF BERYLLIUM WITH ACCEPTOR HYDROCARBONS: ELECTRONIC STRUCTURE AND SECOND HYPERPOLARIZABILITY

Some selected acceptor-Be hydrocarbon complexes have been considered for evaluation of second hyperpolarizability at different DFT functional. All the complexes have been found thermally stable and there is a significant increase of second hyperpolarizability compared to the ligands. Second hyperpolarizability has been explained in terms of charge transfer interaction. Co-operative interaction is required for maximization of second hyperpolarizability. Localized charge transfer in the vicinity of metal alone cannot increase second hyperpolarizability while charge delocalization over entire molecule is mandatory. Substitution by more electropositive metals e.g. Mg , Ca have greater enhancement in longitudinal component of γ. Basis set 6-311++G** is reasonable with respect to computational cost at aug-cc-pVnZ's (n = D, T, Q) for evaluation of second hyperpolarizability for the present complexes.