Volume 122, Issue 4 e26838
RESEARCH ARTICLE

Two projector triple products in quantum crystallography

Chérif F. Matta

Chérif F. Matta

Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Canada

Department of Chemistry, Dalhousie University, Halifax, Canada

Department of Chemistry, Saint Mary's University, Halifax, Canada

Département de Chimie, Université Laval, Québec, Canada

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Lou Massa

Corresponding Author

Lou Massa

Department of Chemistry, Hunter College, City University of New York, New York, New York, USA

Departments of Chemistry and Physics, Graduate Center, City University of New York, New York, New York, USA

Correspondence

Lou Massa, Department of Chemistry, Hunter College, City University of New York, New York, NY 10065, USA.

Email: [email protected]

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First published: 04 December 2021

The results presented in this paper are patterned upon a presentation by L. M. entitled “Quantum Crystallography: N-representability Big and Small” during the Premier Quantum Crystallography Online Meeting (QCrOM2020) at Centrale Supélec, Paris, 26-29 August 2020.

Funding information: Canada Foundation for Innovation, Grant/Award Number: CFI-Leaders Opportunity Fund Grant 2019; Natural Sciences and Engineering Research Council of Canada, Grant/Award Number: NSERC-DG 2015; Mount Saint Vincent University; PSC CUNY Award, Grant/Award Number: 63842-00 41; U.S. Naval Research Laboratory, Grant/Award Number: 47203-00 01

Abstract

Consider a projector matrix P, representing the first order reduced density matrix urn:x-wiley:00207608:media:qua26838:qua26838-math-1001 in a basis of orthonormal atom-centric basis functions. A mathematical question arises, and that is, how to break P into its natural component kernel projector matrices, while preserving N-representability of urn:x-wiley:00207608:media:qua26838:qua26838-math-0001. The answer relies upon 2-projector triple products, P′jPP′j. The triple product solutions, applicable within the quantum crystallography of large molecules, are determined by a new form of the Clinton equations, which—in their original form—have long been used to ensure N-representability of density matrices consistent with X-ray diffraction scattering factors. As such, the goal of this paper is to outline a possible pathway for the application of quantum crystallography to crystals of large molecular systems.

DATA AVAILABILITY STATEMENT

Data sharing not applicable - no new data generated, or the article describes entirely theoretical research

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