Optimized exponents in minimum basis atomic ground state wavefunctions

Abstract

The dependence on the nuclear charge of exponents minimizing the total energy of minimum basis ground state wavefunctions for first and second row atoms and some Ne-like and Ar-like ions is examined. Excellent linear correlations are found with correlation coefficients better than 0.999. Interpretation within a model of screened nuclear charges suggests, in agreement with the classical Slater rules, that s and p electrons with the same n are grouped together and that screening due to outer shell electrons is negligible. In disagreement with these rules, it is found that a multiplying factor different from unity is necessary for 2s and 3s exponents to correct for deficiencies in the functional form of the ns atomic orbitals.