DFT Calculation of Glycine with Methanols Clusters

Density functional theory (DFT) calculations are reported for the structures of neutral andzwitterionic glycine-(CH₃OH)_n where n=1-6. Initial geometries of the clusters of neutral and zwitterionic glycine with 1-6 methanol molecules are fully optimized at B3LYP/6-31+G* level of theory. The lowest energy configurations are located and their hydrogen bond structures are analyzed. Theoretical prediction reveals that the methanols prefer to locate near the carboxylic acid group for the small clusters (n≤3) with the neutral form while the configurations with the methanols bridging the acid and the amino group are favorite in the zwitterionic form clusters. When the number of the methanol molecules in the clusters reaches five and six,the two forms tend to be isoenergetic.