THE DETERMINATION OF HYPERPOLARIZABILITIES USING DENSITY-FUNCTIONAL THEORY

The theory for the calculation of the static polarisability alpha and hyperpolarisability beta using density functional theory is presented. In particular the computational implementation of the coupled-perturb ed Kohn-Sham equations is discussed. Calculations on CH2O and CH3CN ar e reported using large basis sets and accurate quadrature using the lo cal density approximation (S-VWN). The results suggest that DFT is a p romising method for the determination of these properties. Finally it is argued that the theory of Vignale, Rasolt and Geldart can be used a s a basis for the determination of frequency-dependent polarisabilitie s.