Glycine and alanine: a theoretical study of solvent effects upon energetics and molecular response properties

In the present work, we show that polarisable continuum model is able to reproduce the stability of zwitterionic forms of amino acids alanine and glycine in water solution at B3-LYP/6-31G (d) level of theory. The model is then extended to the calculation of vibrational frequencies, Vibrational circular dichroism spectra and nuclear magnetic resonance chemical shifts. The agreement with experimental data is good, except in the case of vibrations where specific hydrogen bond interactions are involved. In the latter case, a supermolecular approach may help in the predictions of some vibrational frequencies of the groups which form hydrogen bonds. (C) 2000 Elsevier Science B.V. All rights reserved.