Approximate Solution of the Representability Problem

1999/07/27 by A. I. Panin, Panin, A. I.
Chemistry · Mathematics · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Chemical Physics (physics.chem-ph) #Chemical Thermodynamics and Molecular Structure #FOS: Physical sciences #History and advancements in chemistry #Mathematical Physics (math-ph) #Quantum Physics (quant-ph) #math-ph #math.MP #physics.chem-ph #quant-ph

paper · pdf · doi:10.48550/arxiv.physics/9907045

LaTeX2e, 45 pages; significantly revised

openalex publication_date 1999/07/27 · arxiv created 2001/02/25 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Approximate solution of the ensemble representability problem for density operators of arbitrary order is obtained. This solution is closely related to the ``Q condition'' of A.J.Coleman. The representability conditions are formulated in orbital representation and are easy to use. They are tested numerically on the base of CI calculation of simple atomic and molecular systems. General scheme of construction of the contraction operator right inverses is proposed and the explicit expression for the right inverse associated with the expansion operator is derived as an example. Two algorithms for direct 2-density matrix determination are described.

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