Efficient open-shell coupled-cluster and perturbation theories
- NASA Ames Research Center, Moffet Field, CA (United States)
A new spin orbital basis is employed in the development of efficient open-shell coupled-cluster and perturbation theories that are based on a restricted Hartree-Fock (RHF) reference function. The spin orbital basis is different from the standard one in the spin functions that are associated with the singly occupied spatial orbital. The occupied orbital (in the spin orbital basis) is assigned the {sigma}{sup +} = 1/{radical}2({alpha} + {beta}) spin function while the unoccupied orbital is assigned the {sigma}{sup {minus}} = 1/{radical}2({alpha} {minus} {beta}) spin function. The doubly occupied and unoccupied orbitals (in the reference function) are assigned the standard {alpha} and {beta} spin orbitals. The coupled-cluster and perturbation theory wave functions based on this set of {open_quotes}symmetric spin orbitals{close_quotes} exhibit much more symmetry than those based on the standard spin orbital basis. This, together with interacting space arguments, leads to a dramatic reduction in the computational cost.
- OSTI ID:
- 141496
- Report Number(s):
- CONF-930304-; TRN: 93:003688-1173
- Resource Relation:
- Conference: 205. American Chemical Society national meeting, Denver, CO (United States), 28 Mar - 2 Apr 1993; Other Information: PBD: 1993; Related Information: Is Part Of 205th ACS national meeting; PB: 1951 p.
- Country of Publication:
- United States
- Language:
- English
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