Dependence of Correlation Energy upon Bond Angle: Investigation of Interactions between Nearly Degenerate Electronic Configurations

Abstract

Configuration interaction of low‐lying electronic states is used to investigate the molecular correlation energy as a function of bond angle. Qualitative aspects of the problem are discussed using the molecular‐orbital diagrams of Walsh and Mulliken. Results of configuration‐interaction calculations of BeH₂ and NO₂⁺ are reported. The possibility of double minima in the potential surfaces for AB₂ molecules is considered.