Role of Core Electrons in Quantum Dynamics Using TDDFT

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Simulating time-dependent electronic processes is computationally intensive.
• Current methods rely on optimizing integration time-steps and reducing computational cost per step.
• Effective core potentials (pseudopotentials) are used to improve efficiency in ground-state calculations.

Purpose of the Study:

• To investigate the impact of effective core potentials on the efficiency of real-time electron dynamics simulations using time-dependent density-functional theory (TDDFT).
• To quantify the performance gains achieved by employing pseudopotentials in these dynamic simulations.

Main Methods:

• Utilized effective core potentials (pseudopotentials) to implicitly represent inner electrons.
• Performed real-time electron dynamics simulations using TDDFT.
• Analyzed the changes in computational cost, density matrix size, and time-step limitations.

Main Results:

• Pseudopotentials achieve significantly greater speedups in real-time dynamics simulations compared to ground-state calculations, reaching up to 600×.
• Performance gains stem from a reduced density matrix size and the elimination of high-frequency electronic modes.
• The elimination of core electron propagation allows for substantial increases in time-step (up to 3 orders of magnitude) without compromising accuracy.

Conclusions:

• Effective core potentials offer a highly efficient approach for real-time electron dynamics simulations.
• This method enables larger time-steps and reduced computational burden, making complex simulations more feasible.
• The use of pseudopotentials in TDDFT simulations is a promising strategy for advancing the study of electronic processes.