Pseudopotential floating spherical gaussian orbital calculations on group IV hydrides

A modification of the floating spherical gaussian orbital (F.S.G.O.) method, in which the core orbitals are replaced by a pseudopotential, is used to perform electronic structure calculations on the series of group IV compounds XH₃, YH₃ (X, Y = C, Si, Ge). The good geometry predictions of the all electron F.S.G.O. method for such group IV compounds are reproduced in the present scheme. In addition a partial improvement of the orbital energies over those of the all-electron F.S.G.O. results for C₂H₆ is observed. Rather good orbital energies are also found for Si ₂H₆. An explanation of this observation is offered.