Theoretical determination of the magnetic properties of HCl, H_2S, PH_3, and SiH_4 molecules

Coupled Hartree–Fock perturbation theory has been applied to evaluate second-order magnetic properties of HCl, H2S, PH3, and SiH4 molecules. An efficient procedure for processing only symmetry distinct two-electron integrals in the coupled HF algorithm is outlined, which permits the use of very large basis sets of expansion with limited computer efforts. Several near Hartree–Fock wave functions are examined, particular attention being devoted to the role of polarization functions for the second-row atoms. Comparison between computed and available experimental results is gratifying and demonstrates the practicability of perturbed HF calculations based on the group-theoretical procedure sketched in this paper. An analysis of the gauge dependence affecting the calculated values is performed, which yields a severe test on the reliability of the present calculations.