Conformational transitions of glycine induced by vibrational excitation of the O-H stretch

Michaela Shmilovits-Ofir, Yifat Miller, R. Benny Gerber

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Vibrational energy flow and conformational transitions following excitation of the OH stretching mode of the most stable conformer of glycine are studied by classical trajectories. "On the fly" simulations with the PM3 semiempirical electronic structure method for the potential surface are used. Initial conditions are selected to correspond to the v = 1 excitation of the OH stretch. The main findings are: (1) An an equilibrium-like ratio is established between the populations of the 3 lowest-lying conformers after about 10 picoseconds. (2) There is a high probability throughout the 150 ps of the simulations for finding the molecule in geometries far from the equilibrium structures of the lowest-energy conformers. (3) Energy from the initial excited OH (v = 1) stretch flows preferentially to 5 other vibrational modes, including the bending motion of the H atom. (4) RRK theory yields conformational transition rates that deviate substantially from the classical trajectory results. Possible implication of these results for vibrational energy flow and conformational transitions in small biological molecules are discussed.

Original languageEnglish
Pages (from-to)8715-8722
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number19
DOIs
StatePublished - 21 May 2011
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (all)
  • Physical and Theoretical Chemistry

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