A Coulomb hole approach to the binding in Cr-2

Artikel i vetenskaplig tidskrift, 1996

The binding in Cr2 is discussed from a semi-quantitative perspective. The static correlation contributions are accounted for by means of restricted active space self-consistent field calculations. The short bond distance in Cr2 is understood to result mainly from near-degeneracies due to states that include the binding 4d pi and 4d delta orbitals. A Coulomb hole expression is employed to estimate the remaining dynamic correlation contributions. Connections are made with aspects of density functional theory, the MGVB method, and recent CAS-PT2 studies.