Dynamic kinetic energy potential for orbital-free density functional theory

Area of Science:

• Computational Physics
• Quantum Chemistry
• Materials Science

Background:

• Orbital-free density functional theory (OF-DFT) excels in static calculations but struggles with dynamic processes.
• Accurate kinetic energy functionals are crucial for simulating electronic system dynamics.
• Existing methods lack efficient ways to capture the dynamic response of electron systems.

Purpose of the Study:

• To develop a dynamic kinetic energy potential (DKEP) for time-dependent OF-DFT (TDOF-DFT).
• To enable TDOF-DFT simulations to accurately mimic the behavior of a non-interacting homogeneous electron gas (HEG) in dynamic scenarios.
• To extend the applicability of OF-DFT from static to dynamic processes.

Main Methods:

• Constructed a DKEP using expansions that involve simple time evolution and spatial convolution.
• Utilized 14 terms in the expansion to accurately fit the HEG response across various frequencies, wavevectors, and densities.
• Demonstrated the method on jellium spheres (Na9+ and Na65+) to validate its performance.

Main Results:

• The DKEP successfully reproduces the dynamic response of the homogeneous electron gas.
• The method is stable for both small and large excitations, showing convergence over time.
• The potential is applicable to a wide range of densities and frequencies.

Conclusions:

• The developed DKEP is a powerful tool for enhancing TDOF-DFT simulations of dynamic processes.
• It facilitates the embedding of accurate dynamical systems (e.g., using TDDFT) within larger TDOF systems.
• The approach offers potential for extensions to experimental or theoretically derived susceptibilities and memory functionals.