Benchmark calculations with correlated molecular wave functions. V. The determination of accurate [ital ab] [ital initio] intermolecular potentials for He[sub 2], Ne[sub 2], and Ar[sub 2]

Journal Article · Tue Feb 15 04:00:00 EST 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.466478· OSTI ID:5283280

Woon, D E ^[1]

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1. Molecular Science Research Center, Pacific Northwest Laboratory, P. O. Box 999, Richland, Washington 99352 (United States)

Dimer interactions of helium, neon, and argon have been studied using the augmented correlation consistent basis sets of Dunning and co-workers. Two correlation methods have been employed throughout; Moller--Plesset perturbation theory through fourth-order (MP4) and single and double excitation coupled-cluster theory with perturbative treatment of triple excitations [CCSD(T)]. Full configuration interaction (FCI) calculations were performed on He[sub 2] for some basis sets. In general, only valence electrons were correlated, although some calculations which also correlated the [ital n]=2 shell of Ar[sub 2] were performed. Dimer potential energy curves were determined using the supermolecule method with and without the counterpoise correction. A series of additional basis sets beyond the augmented correlation consistent sets were explored in which the diffuse region of the radial function space has been systematically saturated. In combination with the systematic expansion across angular function space which is inherent to the correlation consistent prescription, this approach guarantees very accurate atomic polarizabilities and hyperpolarizabilities and should lead to an accurate description of dispersion forces. The best counterpoise-corrected MP4 values for the well depths of the three dimers are (in microhartrees, empirical values in parentheses) He[sub 2], 31.9 (34.6); Ne[sub 2], 123 (134); and Ar[sub 2], 430 (454). The corresponding CCSD(T) values are He[sub 2], 33.1; Ne[sub 2], 128; and Ar[sub 2], 417. Although these values are very good, the nearly exponential convergence of well depth as a function of basis quality afforded by using the various series of correlation consistent basis sets allows estimation of complete basis set (CBS) limiting values. The MP4 estimated CBS limits are He[sub 2], 32.2; Ne[sub 2], 126; and Ar[sub 2], 447.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 5283280
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 100:4; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ARGON
CONFIGURATION INTERACTION
CORRELATION FUNCTIONS
DIMERS
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUIDS
FUNCTIONS
GASES
HELIUM
INTERMOLECULAR FORCES
NEON
NONMETALS
PERTURBATION THEORY
PHYSICAL PROPERTIES
POLARIZABILITY
POTENTIAL ENERGY
RARE GASES
WAVE FUNCTIONS