Comparing thermal wave function methods for multi-configuration time-dependent Hartree simulations

Area of Science:

• Quantum chemistry
• Computational physics
• Chemical dynamics

Background:

• Stochastic temperature wave functions are crucial for accurate simulations of quantum systems.
• The Multi-Configuration Time-Dependent Hartree (MCTDH) method is a powerful tool for simulating the time evolution of quantum systems.
• Efficiently constructing initial wave functions is key to the performance of MCTDH simulations.

Purpose of the Study:

• To compare two distinct methods for generating stochastic temperature wave functions for MCTDH simulations.
• To evaluate the impact of different wave function construction strategies on simulation convergence.
• To identify the most effective approach for improving the efficiency of surface sticking simulations.

Main Methods:

• Method 1: Random selection of Multi-Configuration Time-Dependent Hartree (MCTDH) coefficients.
• Method 2: Construction of a single Hartree product using random single-particle functions (SPFs).
• Application of both methods to a model system for surface sticking dynamics.

Main Results:

• The method employing random single-particle functions (SPFs) demonstrated a significant improvement in convergence.
• Randomly chosen MCTDH coefficients showed slower convergence compared to the random SPF approach.
• The random SPF method proved more efficient for the investigated model system.

Conclusions:

• Using random single-particle functions (SPFs) is a superior strategy for creating stochastic temperature wave functions in MCTDH simulations.
• This approach offers a substantial benefit for achieving faster convergence in surface sticking simulations.
• The findings provide a practical guideline for enhancing the computational efficiency of quantum dynamics simulations.