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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 21, Number 5
BKCSDE 21(5)
May 20, 2000 

 
Title
Quantum Mechanical Study of van der Waals Complex. I. The H2 Dimer Using the DFT and the Multi-Coefficient G2/G3 Methods
Author
Changsihn Kim, Sang Joon Kim, Yongsik Lee, Yongho Kim*
Keywords
Abstract
Molecular hydrogen dimer, (H2)2 is a weakly bound van der Waals complex. The configuration of two hydrogen molecules and the potential well structure of the dimer have been the subjects of various studies among chemists and astrophysicists. ln this study, we used DFT, MCG2, and MCG3 methods to determine the structure and energy of the molecular hydrogen dimer. We compared the results with previously reported ab initiomethod results. The ab initio results were also recalculated for comparison. All optimized geometries obtained from the MP2 and DFT methods are T-shaped. The H-H bond lengths for the dimer are almost the same as those of monomer. The center-to-center distance depends on the levels of theory and the size of the basis sets.The bond lengths of the H2 molecule from the MCG2 and MCG3 methods are shown to be in excellent agreement with the experimental value. The geometry of optimized dimer is T-shaped, and the well depths for the dimerization potential are very small, being 23 cm-l and 27 cm-l at the MCG2 and MCG3 levels, respectively.ln general the MP2 level of theory predicts stronger van der Waals interaction than the DFT, and agrees better with the MCG2 and MCG3 theories.
Page
510 - 514
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