Some Approximate Kohn-Sham Molecular Energy Formulas
Abstract
Density functional calculations have been carried out for twelve molecules by several different Kohn-Sham procedures in order to test the effectiveness of two approximate molecular energy formulas that have been applied earlier in the context of Hartree-Fock theory. The equation E(molecular) = 3/7( (Vne + 2Vnn), in which Vne and Vnn are the nuclear-electronic attraction and nuclear repulsion, reproduces Kohn-Sham energies with an average deviation of less than 0.70%. E(molecular) = alpha.Sigma(ni epsilonj), where ni and epsilonj are the molecular orbital occupancies and energies, gives an average deviation of 1.6%, with alpha determined empirically for each functional combination. The relationship 3E(molecule) = 1.14 Sigma(ni epsilonj) + 2Vnn + Vne, an analogue of an exact Hanree-Fock expression, predicts Becke-3 Kohn-Sham molecular energies to within an average 0.23% of the actual values.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 27, 1998
- Accession Number
- ADA343015
Entities
People
- Fakher Abu-awwad
- Peter Politzer
Organizations
- University of New Orleans