title: Self-trapping of the N-H vibrational mode in alpha-helical polypeptides.
abstract: Recent calculations on the formation of self-trapped amide group vibrational states in alpha-helical polypeptides [J. Chem. Phys. 124, 134907 (2006)] are extended to the amide N-H normal mode vibrations. First, the adiabatic N-H vibrational single- and two-exciton states are examined by treating the longitudinal chain coordinates as parameters. Then, in using the multiconfiguration time-dependent Hartree method coupled exciton-chain vibrational quantum dynamics are accounted for. Based on the respective exciton-chain vibrational wave function propagation the infrared transient absorption related to a sequential pump-probe experiment is calculated. The modulation of local amide vibrational energies by the longitudinal chain coordinates is found to have a pronounced effect on the broadening of absorption lines. Moreover, the ultrafast exciton transfer in the system is studied in order to characterize the dynamics of the self-trapped single-exciton states on a time scale below 10 ps.
authors.affiliation: Institut fur Physik, Humboldt-Universität zu Berlin, D-12489 Berlin, Germany. tsivlin@physik.hu-berlin.de
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Tsivlin
authors.forename: Volkhard
authors.initials: V
authors.lastname: May
mesh_terms: D003198:Computer Simulation; D004735:Energy Transfer; D006859:Hydrogen / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011789:Quantum Theory; D014732:Vibration
chemical_list: D010455:Peptides; D006859:Hydrogen; D009584:Nitrogen