Benchmark calculations with correlated molecular wave functions. III. Configuration interaction calculations on first row homonuclear diatomics

Journal Article · Wed Dec 15 04:00:00 EST 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.465461· OSTI ID:5798718

Peterson, K A; Kendall, R A; Dunning, Jr, T H ^[1]

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1. Molecular Science Research Center, Pacific Northwest Laboratory Richland, Washington 99352 (United States)

Using correlation consistent basis sets from double through quintuple zeta quality, potential energy functions have been calculated for the electronic ground states of the first row homonuclear diatomic molecules B[sub 2], C[sub 2], N[sub 2], O[sub 2], and F[sub 2] using single and double excitation configuration interaction (HF+1+2, GVB+1+2, and CAS+1+2) wave functions. Spectroscopic constants have been calculated for each species and compared to experiment. The dependence of the calculated spectroscopic constants on systematic extensions of the one-particle basis set are, in general, found to be very regular. By fitting the directly calculated values with a simple exponential function, accurate estimates of the complete basis set (CBS) limit for [ital E][sub [ital e]], [ital D][sub [ital e]], and [ital r][sub [ital e]] have been obtained for each level of theory. The estimated CBS limits are compared to the available experimental results, and the [ital intrinsic] errors associated with each theoretical method are discussed. In addition, the accuracy of the internally contracted CAS+1+2 method is compared to conventional uncontracted calculations using large basis sets. For B[sub 2], a full CI calculation have been carried out for [ital D][sub [ital e]] with the correlation consistent double zeta basis set and is compared to the CAS+1+2 method using both a supermolecule and separated atom approach for the dissociated limit.

• DOE Contract Number: AC06-76RL01830; FG06-89ER75522
• OSTI ID: 5798718
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 99:12; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664100* -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
BORON
CARBON
CONFIGURATION INTERACTION
CORRELATIONS
ELECTRON CORRELATION
ELEMENTS
ENERGY
ENERGY LEVELS
ERRORS
FLUORINE
FUNCTIONS
GROUND STATES
HALOGENS
NITROGEN
NONMETALS
OXYGEN
POTENTIAL ENERGY
SEMIMETALS
WAVE FUNCTIONS