Electron-correlation-driven charge migration in oligopeptides

Due to many-body effects an ultrafast removal of an electron from a molecule can trigger electron dynamics in which the created hole charge migrates throughout the system on a few-femtoseconds time scale. Here we report ab initio calculations of the positive-charge migration following inner-valence ionization of the C-terminally methylamidated dipeptide Gly-Gly-NH-CH3. To investigate the influence of the molecular symmetry on the process, two different conformations of the system are studied. Our results show that in both conformers the charge initially localized on the methylamine end of the system migrates to the remote glycine in only 5-6 fs jumping thereby over an entire amino acid. Our computations also show that the symmetry of the system facilitates the process - a larger fraction of the charge migrates over a larger distance if the molecule is symmetric. Ionization spectra of both studied conformers are also reported. (c) 2012 Elsevier B.V. All rights reserved.