Applicability of the LSC-IVR and Its Applications to Absorption Spectra and Electron Transfer Theory

• Main Authors: Hung-Hsuan Teh, 戴宏軒
• Other Authors: Yuan-Chung Cheng
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/81893150268599487234

碩士 === 國立臺灣大學 === 化學研究所 === 102 === In this thesis, we perform theoretical investigations on dynamical processes in condensed phases and spectra by utilizing the linearized semiclassical initial value representation (LSC-IVR) in the Meyer-Miller representation. First, we apply this method to the Frenkel exciton model, determining its applicable regime by comparing the population dynamics with numerically exact quasi adiabatic path integral results. Our calculations suggest that this method gives correct oscillating frequencies but incorrect equilibrium populations. Besides, the decoherence rate are well described as long as the excitonic energy gap is larger compared with the cut-off frequency. We conclude that all the deviations from exact results can be elucidated from the classical approximation in the LSC-IVR method. Moreover, we provide a long time correction, successfully modifying the equilibrium position. Second, we dis- cuss the validity of the LSC-IVR method in simulating the absorption spectra. We demonstrate that it gives excellent results in both monomer and dimer systems. By utilizing the property of less computational expense in this approach, we also successfully reproduce the reasonable absorption lineshape for real complex system. Finally, we consider a dissipative Hamiltonian with a random force and friction yielding a form of Langevin dynamics, where the propagation is based on the LSC-IVR approach, to study the emergence of the Marcus theory. Our results show that there exists an lower and upper bounds in time domain for obtaining Marcus rates. We further find out an universal regime which is suitable for different driving forces.