Electron pair operator approach to coupled cluster wave functions. Application to He/sub 2/, Be/sub 2/, and Mg/sub 2/ and comparison with CEPA methods
A method for obtaining coupled cluster expansions with double substitutions (CCD) utilizing the electron pair operator approach of self-consistent electron pair (SCEP) theory is presented. A fairly simple operator is developed in this method and its calculation increases the expense over a typical variational configuration expansion only moderately. With this method, large basis set calculations have been performed on the weakly interacting dimers He/sub 2/, Be/sub 2/, and Mg/sub 2/. Comparison calculations have been performed with various types of coupled electron pair approximations (CEPA), which may be viewed as approximations to coupled cluster theory, and with modification of the internal orbitals in the CCD treatment.
- Research Organization:
- School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801
- OSTI ID:
- 6534944
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 74:8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BERYLLIUM
POTENTIAL ENERGY
HELIUM
MAGNESIUM
CONFIGURATION INTERACTION
DIMERS
INTERATOMIC FORCES
VAN DER WAALS FORCES
WAVE FUNCTIONS
ALKALINE EARTH METALS
ELEMENTS
ENERGY
FLUIDS
FUNCTIONS
GASES
METALS
NONMETALS
RARE GASES
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory