A comparison model between density functional and wave function theories by means of the L?wdin partitioning technique

摘要

A comparison model is proposed based on the L?wdin partitioning technique to analyze the differences in the treatment of electron correlation by the wave function and density functional models. This comparison model provides a tool to understand the inherent structure of both theories and its discrepancies in terms of the subjacent mathematical structure and the necessary conditions for variationality required for the energy functional. Some numerical results on simple molecules are also reported revealing the known phenomenon of overcorrelation of density functional theory methods.