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 00:00:00 EST 1994 · Journal of Chemical Physics; (United States)

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

Woon, D E ^[1]

---

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), Vol. 100:4; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

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