The importance of long-range electrostatic contributions in Hartree-Fock-Roothaan calculations on model chainlike polymers is stated. The multipole expansion is used to handle them properly. General expressions and working formulas are deduced. Special attention is paid to the Gaussian lobe functions. Applications on ${\left(\mathrm{LiH}\right)}_x$ and ${\left(\mathrm{C}{\mathrm{H}}_2\right)}_x$ chains are made to illustrate the points.

• Received 24 January 1980

DOI:https://doi.org/10.1103/PhysRevB.22.6254