EVALUATION OF INTEGRALS APPEARING IN THE HYLLERAAS CI METHOD BY EXPANDING 1 R(IJ) IN TERMS OF A COMPLETE BASIS-SET/

A new approach for solving multielectronic integrals in quantum chemis try is presented. The Coulomb potential r(12)(-1) is expanded in a com plete function set within a finite spherical domain of radius R. This expansion yields a series where the ($) over right arrow r(1) and ($) over right arrow r(2) variables are symmetrically separated. The gener alization to other potentials is briefly discussed. The Yukawa potenti al exp(-zeta r(12))/r(12), and the functions exp(-zeta r(12)(2)) and e xp(-zeta r(12)) are considered as particular cases. As an example of t he potentialities of this approach, a certain type of four-electron in tegrals that appear in the Hylleraas ci method are evaluated. Results thus obtained are discussed in terms of the approximations made and co mpared with values obtained using other procedures available in the li terature. (C) 1994 John Wiley & Sons, Inc.