TY  - JOUR
A1  - Fischer, Eric W.
A1  - Werther, Michael
A1  - Bouakline, Foudhil
A1  - Saalfrank, Peter
T1  - A hierarchical effective mode approach to phonon-driven multilevel vibrational relaxation dynamics at surfaces
T2  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry
N2  - We discuss an efficient Hierarchical Effective Mode (HEM) representation of a high-dimensional harmonic oscillator bath, which describes phonon-driven vibrational relaxation of an adsorbate-surface system, namely, deuterium adsorbed on Si(100). Starting from the original Hamiltonian of the adsorbate-surface system, the HEM representation is constructed via iterative orthogonal transformations, which are efficiently implemented with Householder matrices. The detailed description of the HEM representation and its construction are given in the second quantization representation. The hierarchical nature of this representation allows access to the exact quantum dynamics of the adsorbate-surface system over finite time intervals, controllable via the truncation order of the hierarchy. To study the convergence properties of the effective mode representation, we solve the time-dependent Schrodinger equation of the truncated system-bath HEM Hamiltonian, with the help of the multilayer extension of the Multiconfigurational Time-Dependent Hartree (ML-MCTDH) method. The results of the HEM representation are compared with those obtained with a quantum-mechanical tier-model. The convergence of the HEM representation with respect to the truncation order of the hierarchy is discussed for different initial conditions of the adsorbate-surface system. The combination of the HEM representation with the ML-MCTDH method provides information on the time evolution of the system (adsorbate) and multiple effective modes of the bath (surface). This permits insight into mechanisms of vibration-phonon coupling of the adsorbate-surface system, as well as inter-mode couplings of the effective bath.
Y1  - 2020
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/58619
SN  - 0021-9606
SN  - 1089-7690
VL  - 153
IS  - 6
PB  - American Institute of Physics
CY  - Melville
ER  -