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Simulation of hydrogen bonding in biological systems: Ab initio calculations for NH 3 NH 3 and NH 3 NH 4 +
Author(s) -
Baird N. Colin
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560080709
Subject(s) - ab initio , hydrogen bond , chemistry , ammonia , dimer , computational chemistry , ab initio quantum chemistry methods , ammonium , morse potential , hydrogen , nitrogen , crystallography , atomic physics , molecule , organic chemistry , physics
Ab initio calculations by Pople's 4–31G method are reported for (NH 3 ) 2 and for NH 3 (NH 4 − ) in order to study the effects of geometric distortions upon NHN hydrogen bonds. The optimum nitrogen‐nitrogen separations are found to be 3.37 and 2.79 Å for linear hydrogen bonds in the ammonia dimer and ammonia ammonium systems, respectively. The variation in energy with distance is well fit by Morse functions in both cases. Energy losses due to displacements of the electron donating NH 3 and due to nonlinearity in the N–H–N bond are also discussed.