State-selective multi-reference coupled-cluster theory employing the single-reference formalism: Application to an excited state of H8

Vadim Alexandrov, Piotr Piecuch, Ludwik Adamowicz

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

The state-selective (SS) multi-reference (MR) coupled-cluster (CC) method exploiting the single-reference (SR) formalism [P. Piecuch, N. Oliphant, and L. Adamowicz, J. Chem. Phys. 99, 1875 (1993)] is applied to the first excited totally symmetric singlet state of a prototype molecular system composed of eight hydrogen atoms. Minimum basis set is employed and various geometries are considered. The SS CC energies are compared with the results of the state-universal (SU) MR CC calculations involving single and double excitations (CCSD) as well as with the exact energies obtained using the full configuration interaction method. Comparison is also made with the results of the standard SR CCSD calculations. In both nondegenerate and quasidegenerate regions, our SS CC theory truncated at double excitations [SS CCSD(TQ) method] provides much better description of the first excited state than the genuine multi-determinantal SU CCSD formalism.

Original languageEnglish (US)
Pages (from-to)3301-3306
Number of pages6
JournalThe Journal of Chemical Physics
Volume102
Issue number8
StatePublished - 1995

Fingerprint

Excited states
formalism
excitation
Hydrogen
configuration interaction
hydrogen atoms
Atoms
prototypes
Geometry
energy
geometry

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

State-selective multi-reference coupled-cluster theory employing the single-reference formalism : Application to an excited state of H8. / Alexandrov, Vadim; Piecuch, Piotr; Adamowicz, Ludwik.

In: The Journal of Chemical Physics, Vol. 102, No. 8, 1995, p. 3301-3306.

Research output: Contribution to journalArticle

@article{123338cae8314a5a87ecd0e7d7568260,
title = "State-selective multi-reference coupled-cluster theory employing the single-reference formalism: Application to an excited state of H8",
abstract = "The state-selective (SS) multi-reference (MR) coupled-cluster (CC) method exploiting the single-reference (SR) formalism [P. Piecuch, N. Oliphant, and L. Adamowicz, J. Chem. Phys. 99, 1875 (1993)] is applied to the first excited totally symmetric singlet state of a prototype molecular system composed of eight hydrogen atoms. Minimum basis set is employed and various geometries are considered. The SS CC energies are compared with the results of the state-universal (SU) MR CC calculations involving single and double excitations (CCSD) as well as with the exact energies obtained using the full configuration interaction method. Comparison is also made with the results of the standard SR CCSD calculations. In both nondegenerate and quasidegenerate regions, our SS CC theory truncated at double excitations [SS CCSD(TQ) method] provides much better description of the first excited state than the genuine multi-determinantal SU CCSD formalism.",
author = "Vadim Alexandrov and Piotr Piecuch and Ludwik Adamowicz",
year = "1995",
language = "English (US)",
volume = "102",
pages = "3301--3306",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "8",

}

TY - JOUR

T1 - State-selective multi-reference coupled-cluster theory employing the single-reference formalism

T2 - Application to an excited state of H8

AU - Alexandrov, Vadim

AU - Piecuch, Piotr

AU - Adamowicz, Ludwik

PY - 1995

Y1 - 1995

N2 - The state-selective (SS) multi-reference (MR) coupled-cluster (CC) method exploiting the single-reference (SR) formalism [P. Piecuch, N. Oliphant, and L. Adamowicz, J. Chem. Phys. 99, 1875 (1993)] is applied to the first excited totally symmetric singlet state of a prototype molecular system composed of eight hydrogen atoms. Minimum basis set is employed and various geometries are considered. The SS CC energies are compared with the results of the state-universal (SU) MR CC calculations involving single and double excitations (CCSD) as well as with the exact energies obtained using the full configuration interaction method. Comparison is also made with the results of the standard SR CCSD calculations. In both nondegenerate and quasidegenerate regions, our SS CC theory truncated at double excitations [SS CCSD(TQ) method] provides much better description of the first excited state than the genuine multi-determinantal SU CCSD formalism.

AB - The state-selective (SS) multi-reference (MR) coupled-cluster (CC) method exploiting the single-reference (SR) formalism [P. Piecuch, N. Oliphant, and L. Adamowicz, J. Chem. Phys. 99, 1875 (1993)] is applied to the first excited totally symmetric singlet state of a prototype molecular system composed of eight hydrogen atoms. Minimum basis set is employed and various geometries are considered. The SS CC energies are compared with the results of the state-universal (SU) MR CC calculations involving single and double excitations (CCSD) as well as with the exact energies obtained using the full configuration interaction method. Comparison is also made with the results of the standard SR CCSD calculations. In both nondegenerate and quasidegenerate regions, our SS CC theory truncated at double excitations [SS CCSD(TQ) method] provides much better description of the first excited state than the genuine multi-determinantal SU CCSD formalism.

UR - http://www.scopus.com/inward/record.url?scp=0042555545&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0042555545&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0042555545

VL - 102

SP - 3301

EP - 3306

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 8

ER -