Intramolecular effects and relative stabilities of conformers of gaseous glycine

Thirteen conformers of nonionized glycine identified previously in ab initi o correlated calculations at the MP2/6-311++G** level of theory are investi gated by means of the atoms in molecules (AIM) theory. The study focuses on properties directly derived from the electron density rho (r). The topolog ical features of p(r) are used to identify intramolecular hydrogen bonds in some structures. The intramolecular effects related with the stability of every conformer are explored by analyzing the potential energy contribution s arising from the molecular fragments NH2, CH2, CO, and OH computed within the AIM framework. This study of intramolecular interactions using informa tion provided by the rho (r) complements previous studies on glycine based on traditional empirical considerations and may be valuable for further stu dies on more complex amino acids.