Ab initio study of the nonadditive effects in the trimer of ammonia
- Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois (USA)
- Molecular Science Software Group, Molecular Science Research Center, Pacific Northwest Laboratory, Richland, Washington (USA)
- 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), Vol. 95:7; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMMONIA
INTERMOLECULAR FORCES
HEITLER-LONDON THEORY
MOLECULAR STRUCTURE
PERTURBATION THEORY
SELF-CONSISTENT FIELD
THREE-BODY PROBLEM
HYDRIDES
HYDROGEN COMPOUNDS
MANY-BODY PROBLEM
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory