Low-energy electron collisions with the alanine molecule

Abstract

A theoretical study on elastic electron collisions with two conformers of amino acid alanine (CH3CH(NH2)COOH) is reported. Differential and integral cross sections are computed for collision energies in the 1-10 eV range. The UK molecular R-matrix codes are used to compute scattering amplitudes within the static exchange plus polarization (SEP) approximation. Both alanine conformers have large permanent dipole moment so to calculate cross sections the Born closure procedure is included to take into account long-range interactions. Comparisons of calculated differential cross sections with available data for glycine are made and display certain similarities. Two shape resonances are detected for each conformer: a narrow one located at 2.7 eV and 3.5 eV which is probably associated with the unoccupied π ∗ orbital of the carboxyl group, and a broader resonance at 8.6 eV and 9.8 eV.