Dynamic treatment of vibrational energy relaxation in a heterogeneous and fluctuating environment

Abstract

A computational approach to describe the energy relaxation of a high-frequency vibrational mode in a fluctuating heterogeneous environment is outlined. Extending previous work [H. Fujisaki, Y. Zhang, and J.E. Straub, J. Chem. Phys. {\bf 124}, 144910 (2006)], second-order time-dependent perturbation theory is employed which includes the fluctuations of the parameters in the Hamiltonian within the vibrational adiabatic approximation. This means that the time-dependent vibrational frequencies along an MD trajectory are obtained via a partial geometry optimization of the solute with fixed solvent and a subsequent normal mode calculation. Adopting the amide I mode of N-methylacetamide in heavy water as a test problem, it is shown that the inclusion of dynamic fluctuations may significantly change the vibrational energy relaxation. In particular, it is found that relaxation occurs in two phases, because for short times ($\lesssim$ 200 fs) the spectral density appears continuous due to the frequency-time uncertainty relation, while at longer times the discrete nature of the bath becomes apparent. Considering the excellent agreement between theory and experiment, it is speculated if this behavior can explain the experimentally obtained biphasic relaxation the amide I mode of N-methylacetamide.

arXiv comment24 pages, 7 figures, submitted to J. Chem. Phys

References in corpus (5)

• Quantum dynamics in strong fluctuating fields
• Time-dependent perturbation theory for vibrational energy relaxation and dephasing in peptides and proteins
• Post-Markov master equation for the dynamics of open quantum systems
• Quantum dynamics of N-methylacetamide studied by the vibrational configuration interaction method
• Quantum and classical vibrational relaxation dynamics of N-methylacetamide on ab initio potential energy surfaces

Cited by in corpus (3)

• Quantum and classical vibrational relaxation dynamics of N-methylacetamide on ab initio potential energy surfaces
• Shape, orientation and magnitude of the curl quantum flux, the coherence and the statistical correlations in energy transport at nonequilibrium steady state
• Mapping energy transport networks in proteins