Multidimensional density operator propagations in open systems: model studies on vibrational relaxations and surface...

Area of Science:

• * Quantum dynamics
• * Surface science
• * Computational chemistry

Background:

• * Open quantum systems present significant numerical challenges.
• * Understanding molecular relaxation and scattering on surfaces is crucial for chemical processes.
• * The multiconfiguration time-dependent Hartree (MCTDH) method is a powerful tool for quantum dynamics.

Purpose of the Study:

• * To extend the MCTDH method for propagating density operators in open systems.
• * To investigate the infrared (IR) pulse-induced relaxation dynamics of a CO molecule on a copper surface (CO/Cu(100)).
• * To analyze scattering processes and calculate sticking coefficients for particles interacting with a model surface heat bath.

Main Methods:

• * Implementation of the multiconfiguration time-dependent Hartree (MCTDH) method for density operator propagation.
• * Application to a CO/Cu(100) system with varying degrees of freedom (2, 4, and 6 DOF).
• * Calculation of sticking coefficients by varying surface corrugation, initial particle energy, and relaxation strengths.

Main Results:

• * The extended MCTDH method efficiently handles multidimensional dynamics of open systems.
• * Lifetime estimations and thermalization studies were performed on IR-excited CO/Cu(100).
• * Sticking coefficients were calculated for scattering processes, demonstrating the method's applicability.

Conclusions:

• * The MCTDH method, extended for density operators, provides an efficient approach for open quantum system dynamics.
• * The study successfully modeled relaxation and scattering phenomena for adsorbed molecules and scattered particles.
• * This work highlights the utility of MCTDH for complex surface dynamics and open environment interactions.