Accurate calculation of the intensity dependence of the refractive index using polarized basis sets.

Using the single and double excitation coupled cluster level of theory (CCSD) and the density functional theory/Becke 3-parameter Lee-Yang and Parr (DFT/B3LYP) methods, we test the performance of the Pol, ZPol, and LPol-n (n = ds, dl, fs, fl) basis sets in the accurate description of the intensity dependence of the refractive index in the Ne atom, and the N(2) and the CO molecules. Additionally, we test the aug-pc-n (n = 1, 2) basis sets of Jensen, and the SVPD, TZVPD, and QZVPD bases by Rappoport and Furche. Tests involve calculations of dynamic polarizabilities and frequency dependent second hyperpolarizabilities. The results are interpreted in terms of the medium constants entering the expressions for optically induced birefringences. In all achiral systems, the performance of the LPol-n sets is very good. Also the aug-pc-2 set yields promising results. Accurate CCSD results available in the literature allow us to select the best basis sets in order to carry out DFT/B3LYP calculations of medium constants in larger molecules. As applications, we show results for (R)-fluoro-oxirane and (R)-methyloxirane.