Kinetic and interaction components of the exact time-dependent correlation potential

Area of Science:

• Quantum Chemistry
• Computational Physics
• Theoretical Chemistry

Background:

• Time-dependent density functional theory (TDDFT) relies on approximations for the exchange-correlation (xc) potential.
• The exact xc potential exhibits complex, non-local features, particularly in non-ground-state situations.
• Understanding these features is crucial for accurate TDDFT simulations.

Purpose of the Study:

• To analyze the exact xc potential by decomposing it into kinetic and interaction components.
• To compare these components with their adiabatic approximations in various dynamical scenarios.
• To investigate the origin of non-adiabatic features in the xc potential.

Main Methods:

• Decomposition of the exchange-correlation potential into kinetic and interaction parts.
• Analysis of one-dimensional, two-electron model systems under different dynamical conditions.
• Comparison of exact xc potential features with adiabatic approximations.

Main Results:

• The kinetic component of the xc potential is often responsible for non-adiabatic features missed by the adiabatic approximation.
• The adiabatic approximation generally performs better for the interaction component.
• Non-adiabatic features in the kinetic component can be significant even without pronounced step structures.

Conclusions:

• The kinetic contribution plays a key role in the non-adiabatic behavior of the exchange-correlation potential.
• The relationship between time-dependent natural orbital occupations and dynamical steps is complex.
• Accurate TDDFT requires careful consideration of the non-adiabatic nature of the xc potential.