Time-dependent density functional theory based Ehrenfest dynamics.

Area of Science:

• Computational Chemistry
• Quantum Dynamics
• Theoretical Physics

Background:

• Accurate simulation of molecular dynamics requires precise treatment of electronic and nuclear motion.
• Traditional methods may not fully capture the interplay between time-dependent electronic states and nuclear movement.

Purpose of the Study:

• To develop and validate a time-dependent density functional theory (TD-DFT) based Ehrenfest dynamics approach.
• To investigate the impact of time-dependent basis functions and density matrix on molecular dynamics.

Main Methods:

• Formulation of electron equations of motion using the first-order reduced density matrix.
• Inclusion of terms accounting for the time-dependence of basis functions on nuclear coordinates.
• Development of an additional term for nuclear force arising from these dependencies.

Main Results:

• The developed TD-DFT Ehrenfest dynamics method incorporates novel terms for electronic and nuclear forces.
• Simulations of H(2) and C(2)H(4) dynamics demonstrate the influence of these new terms.
• The study quantifies the necessity of these additional terms for accurate dynamics.

Conclusions:

• The inclusion of time-dependent basis function effects and the imaginary part of the density matrix is essential.
• This refined approach ensures correct electronic and nuclear dynamics in molecular simulations.
• The developed method provides a more accurate framework for studying quantum dynamics.