A simple polynomial variational-perturbative approach to the evaluation ofdynamic multipole polarizabilities for a ground-state hydrogen atom

Small well-shaped basis sets have been used to perform highly accurate vari ational-perturbative evaluations of dynamic (frequency-dependent) multipole polarizabilities for a hydrogen atom in its ground state. Their structure has been suggested by the ab initio polynomial power expansion we have rece ntly developed to get correspondingly exact results within a finite range c overing the region of low frequencies. The frequency-dependent coefficients of the optimized linear combinations of the excited pseudostate orbitals w ere obtained by diagonalizing the representative matrix of the excitation o perator from the ground state. High levels of accuracy have been observed o ver a set of frequencies now covering the complete real and imaginary range s. (C) 2001 Elsevier Science B.V. All rights reserved.