Single determinant N-representability and the kernel energy method applied to water clusters

Bibliographische Detailangaben
Veröffentlicht in:	Journal of computational chemistry. - 1984. - 39(2018), 17 vom: 30. Juni, Seite 1038-1043
1. Verfasser:	Polkosnik, Walter (VerfasserIn)
Weitere Verfasser:	Massa, Lou
Format:	Online-Aufsatz
Sprache:	English
Veröffentlicht:	2018
Zugriff auf das übergeordnete Werk:	Journal of computational chemistry
Schlagworte:	Journal Article N-representability density matrix quantum crystallography soft scaling quantum chemical methods water clusters

Beschreibung
Zusammenfassung:	© 2017 Wiley Periodicals, Inc. The Kernel energy method (KEM) is a quantum chemical calculation method that has been shown to provide accurate energies for large molecules. KEM performs calculations on subsets of a molecule (called kernels) and so the computational difficulty of KEM calculations scales more softly than full molecule methods. Although KEM provides accurate energies those energies are not required to satisfy the variational theorem. In this article, KEM is extended to provide a full molecule single-determinant N-representable one-body density matrix. A kernel expansion for the one-body density matrix analogous to the kernel expansion for energy is defined. This matrix is converted to a normalized projector by an algorithm due to Clinton. The resulting single-determinant N-representable density matrix maps to a quantum mechanically valid wavefunction which satisfies the variational theorem. The process is demonstrated on clusters of three to twenty water molecules. The resulting energies are more accurate than the straightforward KEM energy results and all violations of the variational theorem are resolved. The N-representability studied in this article is applicable to the study of quantum crystallography. © 2017 Wiley Periodicals, Inc
Beschreibung:	Date Revised 20.11.2019 published: Print-Electronic Citation Status PubMed-not-MEDLINE
ISSN:	1096-987X
DOI:	10.1002/jcc.25064