Non-Markovian vibrational relaxation dynamics at surfaces.

Area of Science:

• Surface science
• Quantum dynamics
• Spectroscopy

Background:

• Vibrational dynamics of adsorbates are crucial for surface science and open quantum system studies.
• A model for D-Si-Si bending mode relaxation on a D:Si(100)-(2 × 1) surface was previously established.
• Phonon bath modes significantly influence adsorbate vibrational dynamics.

Purpose of the Study:

• Extend previous work on vibrational relaxation dynamics.
• Investigate relaxation of higher excited vibrational states.
• Examine scaling laws for vibrational relaxation lifetimes.
• Compare computational efficiency of different quantum dynamics methods.

Main Methods:

• Hierarchical Effective Mode (HEM) model to reduce bath complexity.
• High-dimensional system-bath time-dependent Schrödinger equation (TDSE) solutions.
• Multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) approach.
• Coherent-state-based multi-Davydov-D2 Ansatz.
• Open-system density matrix theory using Liouville-von Neumann (LvN) equation.

Main Results:

• Scaling laws for vibrational relaxation lifetimes were examined for a realistic surface science problem.
• The Hierarchical Effective Mode (HEM) model enabled studying higher excited vibrational states.
• Comparison of ML-MCTDH and multi-Davydov-D2 Ansatz showed computational advantages for the latter.
• Open-system LvN equation quantified effects beyond the Born-Markov approximation.

Conclusions:

• Advanced quantum methods provide insights into adsorbate vibrational dynamics.
• The HEM model offers an efficient approach for studying complex system-bath interactions.
• The multi-Davydov-D2 Ansatz presents a promising alternative for quantum dynamics simulations.
• Accurate modeling of vibration-phonon coupling is essential for understanding surface processes.