Interaction energies associated with short intermolecular contacts of C-H bonds. Ab initio computational study of the C-H{hor_ellipsis} contact interaction in CH{sub 4}{hor_ellipsis}OH{sub 2}.
To accurately evaluate the C-H---O contact interaction energy, ab initio calculations were performed on CH{sub 4}---OH{sub 2} at the self-consistent-field molecular orbital (SCF-MO) and MP2 levels with various quality basis sets including a near Hartree-Fock limit (HFL) one. The interaction energies calculated with truncated basis sets have small basis set superposition errors and become close to the near HFL results only when they include diffuse functions. This is attributed to the necessity of properly representing the lone pair electrons of oxygen that make short contact interaction with the C-H bond. Our MP2 calculations suggest that the conformation of CH{sub 4}---OH{sub 2} with one C-H---O contact is the only minimum-energy structure. At the MP2 level with the near HFL basis set, the binding energy of CH{sub 4}---OH{sub 2} is calculated to be 0.59{+-}0.05 kcal/mol. The potential energy curves of CH{sub 4}---OH{sub 2} calculated as functions of the H---O contact angles are consistent with the observation that the most frequently found H---O contact angles of organic solids are in the range ||{phi}||{le}{approx}60 degrees and ||{theta}||{le}{approx}30 degrees.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- ER
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 937603
- Report Number(s):
- ANL/CHM/JA-977
- Journal Information:
- J. Chem. Phys., Journal Name: J. Chem. Phys. Journal Issue: 7 ; 1991 Vol. 95; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- ENGLISH
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