title: Communication: oscillating charge migration between lone pairs persists without significant interaction with nuclear motion in the glycine and Gly-Gly-NH-CH3 radical cations.
abstract: Coupled electron-nuclear dynamics has been studied, using the Ehrenfest method, for four conformations of the glycine molecule and a single conformation of Gly-Gly-NH-CH3. The initial electronic wavepacket was a superposition of eigenstates corresponding to ionization from the σ lone pairs associated with the carbonyl oxygens and the amine nitrogen. For glycine, oscillating charge migration (when the nuclei were frozen) was observed for the 4 conformers studied with periods ranging from 2 to 5 fs, depending on the energy gap between the lone pair cationic states. When coupled nuclear motion was allowed (which was mainly NH2 partial inversion), the oscillations hardly changed. For Gly-Gly-NH-CH3, charge migration between the carbonyl oxygens and the NH2 lone pair can be observed with a period similar to glycine itself, also without interaction with nuclear motion. These simulations suggest that charge migration between lone pairs can occur independently of the nuclear motion.
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Morgane
authors.initials: M
authors.lastname: Vacher
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bearpark
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Robb