Repulsive intermolecular potential between two H/sub 2/ molecules

Journal Article · Sat Dec 15 04:00:00 EST 1979 · J. Chem. Phys.; (United States)

OSTI ID:5865562

Ree, F H; Bender, C F

Ab initio calculations of the intermolecular potential Phi between two H/sub 2/ molecules have been carried out for intermolecular separations corresponding to the repulsive region of Phi. In most of the calculations a contracted Gaussian basis set consisting of two s and one p functions per H was used to construct a self-consistent field (SCF) configuration and SCF plus all singly and doubly excited configurations at fixed H--H bond length. To ascertain the accuracy of the computed results, three types of more elaborate calculations were carried out. These are based on a larger Gaussian basis set (five s and two p functions per H), full configuration interaction, and variation of the H--H bond length. We found that Phi depends weakly on these factors at r< or approx. =4.5 bohr. Analytic expressions are presented to represent Phi in terms of intermolecular distance and three angles defining orientations of two H/sub 2/ molecules. The minimum-energy orientation of two H/sub 2/ as they approach each other is predicted to have a simple shape, two H/sub 2/ forming a parallelogram. The results obtained in this work are compared with those for other Phi's obtained from theoretical and experimental considerations. Since Phi's based on the condensed-state data are less repulsive than the ab initio Phi, we conclude that the many-body effects in condensed states are significant over a nearly entire range of repulsion.

• Research Organization: Lawrence Livermore Laboratory, University of California, Livermore, California 94550
• OSTI ID: 5865562
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular &amp; Chemical Physics-- Atomic &amp; Molecular Properties &amp; Theory
74 ATOMIC AND MOLECULAR PHYSICS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY
FLUIDS
HYDROGEN
INTERMOLECULAR FORCES
MANY-BODY PROBLEM
MECHANICS
NONMETALS
POTENTIAL ENERGY
QUANTUM MECHANICS