Onehyphen;centerhyphen;expansionmdash;configurationhyphen;interaction calculations have been extended to include higherhyphen;order spherical harmonics and extra radial factors. Calculations have also been made to study the prediction of nuclear geometry. Computations on CH4using as a basis set the orthonormalized Slater atomic orbitals throughl=8, yielded a groundhyphen;state energy of minus;39.94 a.u. Further, the inclusion of additional Schmidt orthogonalized radial factors gave much less improvement than the addition of higher spherical harmonics.The calculations with basis orbitals throughl=4 on NH3failed to predict a nonplanar configuration of minimum energy except for the case where the basis set was truncated to include only orbitals throughl=2. For thel=2 case NH3was predicted to have a nonplanar geometry within one degree of the experimental value.
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