Lagrangian formulation with dissipation of Born-Oppenheimer molecular dynamics using the density-functional...

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Mechanics

Background:

• Born-Oppenheimer molecular dynamics (BOMD) simulations are crucial for understanding molecular behavior.
• The computational cost of BOMD is often limited by the convergence rate of the self-consistent field (SCF) solution.
• Existing DFT-based BOMD methods are typically restricted to short simulation times (tens of picoseconds).

Purpose of the Study:

• To introduce and evaluate a novel dissipative Lagrangian formalism for Born-Oppenheimer molecular dynamics (DXL-BOMD).
• To demonstrate the ability of DXL-BOMD to improve SCF convergence and enhance simulation stability.
• To enable significantly longer molecular dynamics simulations for more meaningful analyses.

Main Methods:

• Developed and implemented the DXL-BOMD algorithm, incorporating an auxiliary electronic variable propagation with a dissipative force.
• Applied DXL-BOMD within the self-consistent charge density functional tight-binding (SCC-DFTB) method.
• Performed NVE simulations of C(2)F(4), amino acids, and water molecules, comparing DXL-BOMD with a standard SCF method.

Main Results:

• DXL-BOMD significantly improves SCF convergence, achieving up to a twofold increase compared to standard methods.
• The DXL-BOMD approach enables simulations of several hundred picoseconds, a substantial increase from previous DFT-based BOMD limitations.
• Analysis using linear response theory clarifies the relationship between energy drift and geometry propagation errors.

Conclusions:

• DXL-BOMD offers a robust and efficient method for accelerating SCF convergence in molecular dynamics.
• The enhanced stability and extended simulation times provided by DXL-BOMD allow for more comprehensive and accurate computational studies.
• This advancement opens possibilities for more in-depth investigations of complex molecular systems and processes.