Modelling fragmentations of aminoacids after resonant electron attachment: quantum evidence of possible direct -OH detachment
Department of Chemistry and CNISM, University of Rome `La Sapienza', Piazzale A. Moro 5, 00185 Roma, Italy
2 CASPUR, Supercomputing Consortium for University and Research, via dei Tizii 6, 00185 Roma, Italy
Corresponding author: a email@example.com
Revised: 11 February 2010
Published online: 2 July 2010
We investigate some aspects of the radiation damage mechanisms in biomolecules, focusing on the modelling of resonant fragmentation caused by the attachment of low-energy electrons (LEEs) initially ejected by biological tissues when exposed to ionizing radiation. Scattering equations are formulated within a symmetry-adapted, single-center expansion of both continuum and bound electrons, and the interaction forces are obtained from a combination of ab initio calculations and a nonempirical model of exchange and correlation effects developped in our group. We present total elastic scattering cross-sections and resonance features obtained for the equilibrium geometries of glycine, alanine, proline and valine. Our results at those geometries of the target molecules are briefly shown to qualitatively explain some of the fragmentation patterns obtained in experiments. We further carry out a one-dimensional (1D) modeling for the dynamics of intramolecular energy transfers mediated by the vibrational activation of selected bonds: our calculations indicate that resonant electron attachment to glycine can trigger direct, dissociative evolution of the complex into (Gly-OH)- and -OH losses, while they also find that the same process does not occur via a direct, 1D dissociative path in the larger aminoacids of the present study.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2010