State-specific multireference complete-active-space coupled-cluster approach versus other quantum chemical methods: Dissociation of the N2 molecule

Dmitry I. Lyakh; Vladimir V. Ivanov; Ludwik Adamowicz

doi:10.1080/00268970701332539

State-specific multireference complete-active-space coupled-cluster approach versus other quantum chemical methods: Dissociation of the N2 molecule

Dmitry I. Lyakh, Vladimir V. Ivanov, Ludwik Adamowicz

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30 Scopus citations

Abstract

A comprehensive comparison of different quantum-chemical methods applied to calculate the N2 ground state potential energy curve is presented. In the comparison we highlight the multireference state-specific (MRSS) coupled-cluster (CC) approach with the complete-active-space (CAS) reference and with single and double excitations from all reference determinants in the CC operator developed in our group. The method is called CASCCSD. The energy and amplitude equations for the method and the corresponding computer code have been generated using a computerized automative procedure that in the present work was extended to produce a parallel computer code. The complete CASCCSD wave function for N2 includes some selected eight-fold excitations in the CC operator. An analysis of the wave function estimates the importance of those excitations at large internuclear separations.

Original language	English (US)
Pages (from-to)	1335-1357
Number of pages	23
Journal	Molecular Physics
Volume	105
Issue number	10
DOIs	https://doi.org/10.1080/00268970701332539
State	Published - May 2007

ASJC Scopus subject areas

Biophysics
Molecular Biology
Condensed Matter Physics
Physical and Theoretical Chemistry

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10.1080/00268970701332539

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title = "State-specific multireference complete-active-space coupled-cluster approach versus other quantum chemical methods: Dissociation of the N2 molecule",

abstract = "A comprehensive comparison of different quantum-chemical methods applied to calculate the N2 ground state potential energy curve is presented. In the comparison we highlight the multireference state-specific (MRSS) coupled-cluster (CC) approach with the complete-active-space (CAS) reference and with single and double excitations from all reference determinants in the CC operator developed in our group. The method is called CASCCSD. The energy and amplitude equations for the method and the corresponding computer code have been generated using a computerized automative procedure that in the present work was extended to produce a parallel computer code. The complete CASCCSD wave function for N2 includes some selected eight-fold excitations in the CC operator. An analysis of the wave function estimates the importance of those excitations at large internuclear separations.",

author = "Lyakh, {Dmitry I.} and Ivanov, {Vladimir V.} and Ludwik Adamowicz",

note = "Funding Information: This work has been supported by the National Science Foundation. DIL would like to thank the Kharkiv National University Foundation for partial support of his contribution to this work.",

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T2 - Dissociation of the N2 molecule

AU - Lyakh, Dmitry I.

AU - Ivanov, Vladimir V.

AU - Adamowicz, Ludwik

N1 - Funding Information: This work has been supported by the National Science Foundation. DIL would like to thank the Kharkiv National University Foundation for partial support of his contribution to this work.

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N2 - A comprehensive comparison of different quantum-chemical methods applied to calculate the N2 ground state potential energy curve is presented. In the comparison we highlight the multireference state-specific (MRSS) coupled-cluster (CC) approach with the complete-active-space (CAS) reference and with single and double excitations from all reference determinants in the CC operator developed in our group. The method is called CASCCSD. The energy and amplitude equations for the method and the corresponding computer code have been generated using a computerized automative procedure that in the present work was extended to produce a parallel computer code. The complete CASCCSD wave function for N2 includes some selected eight-fold excitations in the CC operator. An analysis of the wave function estimates the importance of those excitations at large internuclear separations.

AB - A comprehensive comparison of different quantum-chemical methods applied to calculate the N2 ground state potential energy curve is presented. In the comparison we highlight the multireference state-specific (MRSS) coupled-cluster (CC) approach with the complete-active-space (CAS) reference and with single and double excitations from all reference determinants in the CC operator developed in our group. The method is called CASCCSD. The energy and amplitude equations for the method and the corresponding computer code have been generated using a computerized automative procedure that in the present work was extended to produce a parallel computer code. The complete CASCCSD wave function for N2 includes some selected eight-fold excitations in the CC operator. An analysis of the wave function estimates the importance of those excitations at large internuclear separations.

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State-specific multireference complete-active-space coupled-cluster approach versus other quantum chemical methods: Dissociation of the N2 molecule

Abstract

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