AB-INITIO DETERMINATION OF THE NUCLEAR-RELAXATION CONTRIBUTION TO THE2ND-HYPERPOLARIZABILITY OF CARBON-DISULFIDE

Although basis set saturation, electron correlation and frequency disp ersion have been addressed thoroughly, the electronic second hyperpola rizability of carbon disulfide computed by K. Ohta, T. Sakaguchi: K. K amada and T. Fukumi (Chem. Phys. Lett. 274 (1997) 306) is not in agree ment with experiment. In this Letter the potentially substantial nucle ar relaxation contribution is evaluated within the Moller-Plesset sche me limited to second order by using the 6-31G basis set augmented by three diffuse functions (Ip and 2d). Within the enhanced approximation , the nuclear relaxation contribution to the static, dc-Kerr and ESHG second hyperpolarizability turns out to amount to 26.5%, 6.8% and -0.8 % of the pure static electronic counterpart, respectively. The remaini ng gap between theory and experiment suggests new experiments should b e carried out. (C) 1998 Elsevier Science B.V. All rights reserved.