A new formulation of scaled atoms-in-molecules theory

• Published in: The Journal of chemical physics 1983-09, Vol.79 (5), p.2278-2283
• Main Author: ELLISON, F. O
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics; Valence bond calculations
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.446078

In scaled atoms-in-molecules theory, variational scaling parameters are introduced into the A- and B-atom eigenfunctions from which molecular basis functions are constructed. All intraatomic contributions to matrix elements are determined rigorously in terms of scaling parameters and experimental atomic state energies. Approximate atomic state eigenfunctions are used to compute interatomic contributions. Ground and excited state energy roots of the resulting molecular eigenvalue problem can be independently minimized with respect to the scaling parameters. The original formulation of theory (SAIM.V) employed atomic potential energy operators as part of the intraatomic correction due to scaling. A new formulation (SAIM.T) using atomic kinetic energy operators in this role is tested in calculations on H2, HeH+, He+2, and HeH. The simpler SAIM.T formulation is found to give results of the same quality as the original SAIM.V version.