The Effect of Bond Function Polarization on the l.c.a.o.–m.o.–s.c.f. Calculation of Bond Angles and Energy Barriers

The effect of including polarization into a flexible s, p basis set by use of bond functions is studied in the systems H2O, NH3, H2O2, and N2H4. In all cases a decrease and subsequent improvement in calculated bond angles is found. Barriers to nitrogen inversion are also significantly improved. Bond function polarization alone does not account for the anti rotation barrier in H2O2 although it does lead to stabilization of the gauche form relative to the anti form. The effect on molecular charge distributions is to allow movement of charge into the bonding regions. The results indicate that bond functions are an efficient means of introducing polarization into a basis set and lead to an improved agreement between calculated and experimental geometric and energetic parameters.