SIMPLE FINITE-FIELD METHOD FOR CALCULATION OF STATIC AND DYNAMIC VIBRATIONAL HYPERPOLARIZABILITIES - CURVATURE CONTRIBUTIONS

In the static field limit, the vibrational hyperpolarizability consist s of two contributions due to: (1) the shift in the equilibrium geomet ry (known as nuclear relaxation), and (2) the change in the shape of t he potential energy surface (known as curvature). Simple finite field methods have previously been developed for evaluating these static fie ld contributions and also for determining the effect of nuclear relaxa tion on dynamic vibrational hyperpolarizabilities in the infinite freq uency approximation. In this paper the finite field approach is extend ed to include, within the infinite frequency approximation, the effect of curvature on the major dynamic nonlinear optical processes. (C) 19 98 American Institute of Physics.