Approaching exact hyperpolarizabilities via sum-over-states Monte Carlo configuration interaction

作者：Coe J P^*; Paterson M J

来源：Journal of Chemical Physics, 2014, 141(12): 124118.

DOI：10.1063/1.4896229

We propose using sum-over-states calculations with the compact wavefunctions of Monte Carlo configuration interaction to approach accurate values for higher-order dipole properties up to second hyperpolarizabilities in a controlled way. We apply the approach to small systems that can generally be compared with full configuration interaction (FCI) results. We consider hydrogen fluoride with a 6-31g basis and then look at results, including frequency dependent properties, in an aug-ccp-VDZ basis. We extend one calculation beyond FCI by using an aug-cc-pVTZ basis. The properties of an H-4 molecule with multireference character are calculated in an aug-cc-pVDZ basis. We then investigate this method on a strongly multireference system with a larger FCI space by modelling the properties of carbon monoxide with a stretched geometry. The behavior of the approach with increasing basis size is considered by calculating results for the neon atom using aug-cc-pVDZ to aug-cc-pVQZ. We finally test if the unusual change in polarizability between the first two states of molecular oxygen can be reproduced by this method in a 6-31g basis.

• 出版日期2014-9-28