Irreducible charge density matrices for analysis of many‐electron wave functions

摘要: A novel procedure for deriving multicenter bond indices on the basis of irreducible spinless charge density matrices that are naturally introduced as in Ursell-Mayer theory is presented. Unlike earlier schemes using central moments operator, presented here leads to a proper definition an arbitrary number atoms. Formal relationships and numerical techniques typical configuration interaction (CI) approaches, up full CI, given illustrated with simple molecular systems. Comparison orbital CI results indicates strong electron correlation effects, especially 3-center 4-center indices. Excited state described within singles approach. The problem atomic valence electronic states nonzero spin raised.