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Orbital correlation effects II. Potential curve and ionization potential of boron hydride
Author(s) -
Mehler E. L.,
Van Der Velde G. A.,
Nieuwpoort W. C.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560090831
Subject(s) - boron , hydride , chemistry , ionization energy , ionization , computational chemistry , electronic correlation , atomic physics , molecular physics , physics , molecule , ion , metal , organic chemistry
With the help of the independent pair‐potential approximation (ippa) the valence‐shell correlation effects in BH have been calculated at nine internuclear separations. The results are compared with several other methods, including the coupled electron pair approximation (cepa) and a full configuration interaction expansion. The stability of the ippa against a unitary transformation of the occupied orbitals has also been investigated, and it is shown that the ippa is nearly invariant against such transformations. The Dunham procedure has been applied to the results, and the spectroscopic constants obtained from the various approximations are compared. It is furthermore demonstrated that many of the defects present in the Hartree‐Fock part of the potential curve and arising from the use of medium‐quality basis sets can be eliminated by combining the correlation results with Hartree Fock results from good‐quality basis sets and reapplying the Dunham procedure. Finally the ippa has been applied to BH + , and the first vertical ionization potential of BH was determined.