DOI: 10.1063/1.455822. The unrestricted natural orbital–complete active space (UNO–CAS) method: An inexpensive alternative to the complete active space–self-consistent-field (CAS

The unrestricted natural orbital–complete active space (UNO–CAS) method: An inexpensive alternative to the complete active space–self-consistent-field (CAS–SCF) method

10.1063/1.455822

Crossref journal-article

AIP Publishing

The Journal of Chemical Physics (317)

Abstract

Full configuration interaction in the space of fractionally occupied unrestricted Hartree–Fock natural orbitals is proposed as an inexpensive alternative to the complete active space–self-consistent-field method for ground states. In most cases, this method requires only a fraction of the computational effort of the latter and gives comparable results, as demonstrated on several examples. Gradient evaluation, while more complex in formulation, is computationally not significantly more expensive than unrestricted Hartree–Fock gradients.

Bibliography

Bofill, J. M., & Pulay, P. (1989). The unrestricted natural orbitalâcomplete active space (UNOâCAS) method: An inexpensive alternative to the complete active spaceâself-consistent-field (CASâSCF) method. The Journal of Chemical Physics, 90(7), 3637â3646.

Authors 2

Josep M. Bofill (first)
Peter Pulay (additional)

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Dates

Type	When
Created	23 years ago (July 26, 2002, 9:10 a.m.)
Deposited	1 year, 6 months ago (Feb. 10, 2024, 4:33 a.m.)
Indexed	1 week, 3 days ago (Aug. 12, 2025, 5:29 p.m.)
Issued	36 years, 4 months ago (April 1, 1989)
Published	36 years, 4 months ago (April 1, 1989)
Published Print	36 years, 4 months ago (April 1, 1989)

Funders 0

None

BibTeX

@article{Bofill_1989, title={The unrestricted natural orbital–complete active space (UNO–CAS) method: An inexpensive alternative to the complete active space–self-consistent-field (CAS–SCF) method}, volume={90}, ISSN={1089-7690}, url={http://dx.doi.org/10.1063/1.455822}, DOI={10.1063/1.455822}, number={7}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Bofill, Josep M. and Pulay, Peter}, year={1989}, month=apr, pages={3637–3646} }

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