Construction of a Perfectly N-Representable Two-Electron Density Matrix Carrying Full Information on an Interacting System

Abstract

The two-particle density matrix contains all information, which is "readable" by one- and two-particle operators. The report discusses the building of a two-electron density matrix, which is perfectly N-representable by construction. The 2-matrix of a pure quantum state is obtained without the intermediate determination of the wave function. The procedure is illustrated by computations on atomic and small molecular systems.

A novel approach for calculating correlation energy based on the two‐electron density matrix formalism

“…All of the above structure‐dependent properties of the V tensors are closely related to the manner of contraction of the N ‐particle information to two‐particle information. Some further properties are dealt with in 15, 19.…”

“…The optimization of the two‐electron density matrix requires M 4 ‐scaling parameters, where M is the dimension of the one‐electron function basis. This work is illustrated with examples on atomic and molecular computations, while further details are given in 15, 19.…”