Ab initio study of the nonadditive effects in the trimer of ammonia

Journal Article · Tue Oct 01 04:00:00 EDT 1991 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.461685· OSTI ID:5254208

Szczesniak, M M ^[1]; Kendall, R A ^[2]; Chalasinski, G ^[3]

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1. Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois (USA)
2. Molecular Science Software Group, Molecular Science Research Center, Pacific Northwest Laboratory, Richland, Washington (USA)
3. Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois (USA) Department of Chemistry, University of Warsaw, Pasteura 1, 02-093, Warszawa (Poland)

The three-body potential in the trimer of ammonia is analyzed in terms of Heitler--London (HL)-exchange, self-consistent field (SCF)-deformation, induction, and dispersion nonadditivities. The nonadditive term is due largely to the SCF-deformation effect. However, its anisotropy resembles more that of the HL-exchange nonadditivity. Correlation effects do not contribute significantly to the nonadditivity. The trimer is of {ital C}{sub 3{ital h}} symmetry. The geometry is determined at the level of pairwise interactions. Apart from a slight shortening of the N----N distance, the three-body effect has virtually no influence on the mutual orientations of subsystems in the trimer. Nonadditive properties of ammonia are compared to those of other trimers: (HF){sub 3}; (HCl){sub 3}; (H{sub 2}O){sub 3}; and (CH{sub 4}){sub 3}. An examination of the basis set dependence of the components of three-body effect leads us to believe that the present treatment yields three-body potential with accuracy better than 0.1 kcal/mol for the trimer of ammonia, as well as for other polar trimers.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 5254208
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 95:7; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
AMMONIA
HEITLER-LONDON THEORY
HYDRIDES
HYDROGEN COMPOUNDS
INTERMOLECULAR FORCES
MANY-BODY PROBLEM
MOLECULAR STRUCTURE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
PERTURBATION THEORY
SELF-CONSISTENT FIELD
THREE-BODY PROBLEM