Abstract
We investigate isotope effects in dihydrogen systems using the nuclear orbital plus molecular orbital (NOMO) theory, which simultaneously determines nuclear and electronic wave functions without the Born-Oppenheimer approximation. In order to estimate the vibrational averaging bond distances, the analytical energy gradients are used for the NOMO theory. The bond distances of three dihydrogen-bonded systems, namely H3NX+ XBeH, LiX XC2H and H2BX XF for X = H, D and T, are obtained. The X X bond distances decrease with respect to the substitution T D H, which is contrary to the behaviour of typical hydrogen bonds. This indicates that isotope effects strengthen the X X bond. This behaviour is analogous to the Ubbelohde effect observed in the solid phase.
Original language | English |
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Pages (from-to) | 2649-2657 |
Number of pages | 9 |
Journal | Molecular Physics |
Volume | 105 |
Issue number | 19-22 |
DOIs | |
Publication status | Published - 2007 Oct 21 |
Keywords
- Analytical energy gradient
- Dihydrogen-bonded system
- Isotope effect
- Nuclear orbital plus molecular orbital theory
- Vibrational averaging shift
ASJC Scopus subject areas
- Biophysics
- Molecular Biology
- Condensed Matter Physics
- Physical and Theoretical Chemistry