Ab-initio MO calculations of electric field gradients at Cl-35 and H-2 nuclei in SiH3Cl, SiH2Cl2, SiCl2 and SiHCl3 molecules

The electric field gradients and nuclear quadrupole coupling constants of C l-35 and H-2 nuclei in SiH3Cl, SiCl2, SiH2Cl2 and SiHCl3 molecules have bee n calculated using 6-31G and [6s6p/3s/7s5p] basis sets employing ab-initio optimized geometry. The effect of augmentation by s and p, and s, p, and d bond centered functions and/or nuclear centered polarization functions to t he basis sets have been studied. The study illustrates that basis sets with bond functions are generally adequate to obtain reasonable values of elect ric field gradients and quadrupole couplings, which db not change much on f urther enlargement of basis sets. Most of the contribution (around 90%) to the total electric field gradient is due to the valence molecular orbitals.