Exploiting the nearsightedness principle within the framework of the anti‐Hermitian contracted Schrödinger equation

This work exploits the Kohn nearsightedness principle in the algorithms arising from the anti‐Hermitian contracted Schrödinger equation. The procedure provides the implementation of approximations yielding a considerable saving of computational costs in descriptions of N‐electron molecular systems b...

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Bibliographic Details
Published in:	International journal of quantum chemistry Vol. 122; no. 6
Main Authors:	Honoré, Eduardo M., Ríos, Elías, Alcoba, Diego R., Massaccesi, Gustavo E., Torre, Alicia, Lain, Luis, Oña, Ofelia B.
Format:	Journal Article
Language:	English
Published:	Hoboken, USA John Wiley & Sons, Inc 15-03-2022 Wiley Subscription Services, Inc
Subjects:	Algorithms Approximation Chemistry Configuration interaction contracted Schrödinger equation Density local property localization procedure Molecular orbitals nearsightedness principle Physical chemistry Quantum physics reduced density matrix Schrodinger equation
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Summary:	This work exploits the Kohn nearsightedness principle in the algorithms arising from the anti‐Hermitian contracted Schrödinger equation. The procedure provides the implementation of approximations yielding a considerable saving of computational costs in descriptions of N‐electron molecular systems by means of that technique. We report energies, at correlated level, of linear hydrogen chains designed at different geometries, so that we can analyze the strength of the interactions between first‐, second‐, third‐, fourth‐, and so forth neighbor atoms. Using localized molecular orbital basis sets, we observe rapid decays in the values of the elements of the reduced‐density‐matrix cumulant matrices, beyond a cut‐off radius, which justify the proposed approximations. The results, in terms of energies and reduced density matrices, have been compared with those obtained from the full configuration interaction method, showing the usefulness of the nearsightedness principle in this methodology. Computational costs demanded in the description of electronic correlation when the nearsightedness principle is applied within the anti‐Hermitian contracted Schrödinger equation framework, using a localized basis set. Neglecting the interactions between atoms beyond a reduced number of neighbors yields suitable results requiring a markedly lower computational effort.
Bibliography:	Funding information Agencia Nacional de Promoción Científica y Tecnológica, Grant/Award Number: PICT‐201‐0381; Consejo Nacional de Investigaciones Científicas y Técnicas, Grant/Award Numbers: PIP 11220130100311CO, PIP 11220130100377CO, PIP 11220200100467CO; Universidad de Buenos Aires, Grant/Award Number: 20020190100214BA
ISSN:	0020-7608 1097-461X
DOI:	10.1002/qua.26862