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Wolfgang Förner Peter Otto Julius Bernhardt János J. Ladik 《Theoretical chemistry accounts》1981,60(3):269-281
We have performed calculations of the glycine zwitterion surrounded by water molecules with the help of the mutually consistent
field (MCF) method and perturbation theoretical expressions. Two different models for the hydration shell have been chosen,
the glycine·6H2O and glycine·12H2O complexes, representing the most probable first and second solvation shell, respectively. To calculate the exchange and
charge transfer energy contributions we have applied approximative expressions derived from perturbation theory for weakly
overlapping subunits. For the sake of comparison we also calculated the interaction energy in the supermolecule approach for
the smaller of the two solvation complexes. Furthermore, we have investigated the part of the potential energy surface which
is determined by varying the lengths of the hydrogen bonds between glycine and water in the complex glycine·12H2O using the electrostatic approach. The exchange energy contribution to the interaction energy for different points on the
surface was approximated with the help of an analytical expression fitted to three directly calculated points. For the charge
transfer energy a polynomial expansion of second order was established on the basis of five values, computed with the aid
of the perturbation theoretical expression. To get a more detailed insight in the relatively strong hydrogen bonds between
the water molecules and the ionic hydrophilic parts of glycineab initio model studies on NH
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·3H2O and HCOO−·3H2O systems are reported. 相似文献
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