title: Time-dependent perturbation theory for vibrational energy relaxation and dephasing in peptides and proteins.
abstract: Without invoking the Markov approximation, we derive formulas for vibrational energy relaxation (VER) and dephasing for an anharmonic system oscillator using a time-dependent perturbation theory. The system-bath Hamiltonian contains more than the third order coupling terms since we take a normal mode picture as a zeroth order approximation. When we invoke the Markov approximation, our theory reduces to the Maradudin-Fein formula which is used to describe the VER properties of glass and proteins. When the system anharmonicity and the renormalization effect due to the environment vanishes, our formulas reduce to those derived by and Mikami and Okazaki [J. Chem. Phys. 121, 10052 (2004)] invoking the path-integral influence functional method with the second order cumulant expansion. We apply our formulas to VER of the amide I mode of a small amino-acid like molecule, N-methylacetamide, in heavy water.
authors.affiliation: Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA. fujisaki@bu.edu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fujisaki
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: John E
authors.initials: JE
authors.lastname: Straub
mesh_terms: D000577:Amides / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods*; D008390:Markov Chains; D008956:Models, Chemical; D015233:Models, Statistical; D008962:Models, Theoretical; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000577:Amides; D010455:Peptides; D014867:Water