Stable Occupancy of Hydrogen Molecules in H2 Clathrate Hydrates and H2 + THF Clathrate Hydrates Determined by Ab Initio Calculations. (8th November 2009)

• Record Type: Journal Article
• Authors: Yedlapalli, Prasad; Lee, Sangyong; Lee, Jae W.
• Other Names: Lucia Angelo Academic Editor.
• Is Part Of: Journal of thermodynamics. Volume 2010(2010)
• Publication Date: 2009-11-08
• Subjects: Thermodynamics -- Periodicals; Thermodynamics; Periodicals; Electronic journals; 536.7
• DOI: 10.1155/2010/651819
• Languages: English
• ISSNs: 1687-9244

Abstract

Abstract : Structure II clathrate hydrates of pure hydrogen and binary hydrates ofTHF + H 2 are studied using ab initio calculations to determine the stable occupancies of small cavities. Ab initio calculations are carried out for a double cavity consisting of one dodecahedron (small cavity) and one hexakaidecahedron (large cavity). These two cavities are attached to each other as in sII hydrates to form a double cavity. One or twoH 2 molecules are placed in the small cavity and one THF (or 4H 2 molecules) molecule is placed in the large cavity. We have determined the binding energies of the double cavities at the MP2 level using various basis sets (3-21G, 3-21G(2p), 3-21+ + G(2p), 6-31G, 6-31G(2p), and 6-31+ + G(2p)). Different basis sets yield different stable occupancies of the small cavity. The results from the highest basis set (6-31+ + G(2p) with zero point energy corrections) indicate that the single occupancy is slightly more favorable than the double occupancy in both the cases of pureH 2 hydrates and THF +H 2 double hydrates.