LCAO-MO-SCF calculations using Gaussian basis functions. XI. BeNe and BeAr. Desirable criteria for atomic contraction coefficients for molecular formation and valence-shell correlation

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Abstract
Ab initio LCAO‐MO‐SCF calculations of the lowest 1Σ+ states of BeNe and BeAr showed that the systems were both repulsive. Population analyses indicated that there was only a very small amount of π electron density transferred from the rare gas π orbitals to the empty π orbitals on the boron. Examination of the SCF gross atomic populations of both the occupied and unoccupied orbitals led to several interesting observations. First, it seems possible to identify, merely from the SCF gross population analyses, which virtual molecular orbitals will correlate uniquely certain of the occupied molecular orbitals. This could be very useful in enabling one to truncate expeditiously a set of virtual orbitals. Second, several choices for contracting an 11 s 6 p atomic Gaussian basis set for first row atoms and a 17 s 12 p atomic Gaussian basis set for second row atoms better suited to describe molecular formation and virtual orbitals for valence shell configurations are suggested.