Interactions energies associated with short intermolecular contacts of C--H bonds. II. Ab initio computational study of the C--Hter dot ter dot ter dot H--C interactions in methane dimer
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204 (USA)
- Chemistry and Materials Science Divisions, Argonne National Laboratory, Argonne, Illinois 60439 (USA)
On the basis of single-and multireference {ital ab} {ital initio} calculations on (Be){sub 2} and (H{sub 2}){sub 2}, we suggest that van der Waals systems with large highest occupied molecular orbital--lowest unoccupied molecular orbital gap can be reasonably well described by single reference MP{ital n} ({ital n}=2--4) calculations if the basis set is large enough. The binding energies of C--H{center dot}{center dot}{center dot}H--C contacts are then examined by performing single reference MP{ital n} calculations on (CH{sub 4}){sub 2} dimer. Our study shows that (CH{sub 4}){sub 2} is bound in all possible CH{sub 4}{center dot}{center dot}{center dot}CH{sub 4} arrangements, and that those arrangements with more than one C--H{center dot}{center dot}{center dot}H--C contact lead to a greater amount of stabilization than does the arrangement with one C--H{center dot}{center dot}{center dot}H--C contact. The potential energy curves obtained for staggered arrangements of (CH{sub 4}){sub 2} by the MP2 calculations with the 6-311G(2{ital d},2{ital p}) basis set are in close agreement with the experimentally deduced, isotropic potential curve.
- DOE Contract Number:
- FG05-86ER45259; W-31109-ENG-38
- OSTI ID:
- 5882340
- Journal Information:
- Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 94:7; ISSN JCPSA; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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