EFFICIENT PROCEDURE TO EVALUATE LONG-RANGE COULOMBIC INTERACTIONS WITHIN FRAMEWORK OF LCAO-CO METHOD FOR INFINITE POLYMERS

A very efficient and exact method for calculating the long‐range effects in polymers is reported. The method is based on the multipole expansion within the Fock operator, and exact summation up to infinity is carried out. Only a small number of one‐electron integrals have to be considered, while in the traditional approach one has to compute a large number of two‐electron integrals. Results on LiH model polymer have been obtained with a remarkable accuracy within a negligible computing time. Copyright © 1978 John Wiley & Sons, Inc.