Quantum Crystallography: Projectors and kernel subspaces preserving N-representability
Quantum Physics
2021-09-09 v1 Biomolecules
Abstract
Consider a projector matrix P, representing the first order reduced density matrix 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 P. 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.
Cite
@article{arxiv.2109.03388,
title = {Quantum Crystallography: Projectors and kernel subspaces preserving N-representability},
author = {Cherif F. Matta and Lou Massa},
journal= {arXiv preprint arXiv:2109.03388},
year = {2021}
}