Generalized extended Lagrangian Born-Oppenheimer molecular dynamics

Area of Science:

• Computational chemistry
• Materials science
• Condensed matter physics

Background:

• Extended Lagrangian Born-Oppenheimer molecular dynamics (XL-BO) is crucial for simulating quantum systems.
• Current XL-BO methods often require computationally expensive self-consistent field (SCF) optimizations.
• Accurate simulation of electronic and nuclear dynamics is essential for understanding material properties.

Purpose of the Study:

• To generalize XL-BO molecular dynamics by minimizing SCF optimization steps.
• To derive new equations of motion that inherently handle adiabatic separation of nuclear and electronic degrees of freedom.
• To enhance the accuracy, stability, and applicability of XL-BO simulations.

Main Methods:

• Derivation of equations of motion from an extended Lagrangian.
• Implementation within the Kohn-Sham density functional theory (DFT) framework.
• Focus on the limit of vanishing SCF optimization before force evaluations.

Main Results:

• A generalized formulation requiring only one diagonalization per time step.
• Demonstration of automatic and system-independent fulfillment of adiabatic separation.
• Improved accuracy and stability compared to existing XL-BO methods.

Conclusions:

• The generalized XL-BO method offers a more efficient and robust approach for DFT-based molecular dynamics.
• This advancement expands the applicability of accurate simulations to a wider range of materials.
• The reduced computational cost per time step facilitates larger and longer simulations.