Structure and ESR features of a radiation-induced radical in alpha-glycine crystals

Extensive DFT calculations are reported for the carbon centered glycine radical embedded in a-glycine crystal. Combined use of periodic and embedded cluster models leads to accurate structural and magnetic properties. Environmental effects are not negligible for all properties, whereas vibrational averaging effects connected to inversion at the radical center are significant only for C-alpha and H-alpha atoms. The good agreement between computed and experimental ESR parameters confirms the nature of one of the radicals obtained upon irradiation of a-glycine crystals and the reliability of DFT computations properly including both vibrational averaging and environmental effects. (c) 2007 Elsevier B.V. All rights reserved.