Stochastic Constrained Extended System Dynamics for Solving Charge Equilibration Models.

Area of Science:

• Computational Chemistry
• Materials Science
• Molecular Dynamics

Background:

• Accurate charge distribution is crucial for molecular simulations.
• Standard self-consistent field (SCF) methods present a computational bottleneck.
• Existing methods struggle with computational efficiency for complex systems.

Purpose of the Study:

• To introduce a novel stochastic extended Lagrangian molecular dynamics (SC-XLMD) method.
• To eliminate the need for computationally expensive SCF calculations in charge equilibration.
• To enable accurate and efficient simulations of molecular systems.

Main Methods:

• Formulated charges and chemical potential as latent variables.
• Introduced a holonomic constraint for charge conservation.
• Applied the SC-XLMD method within the ReaxFF framework.

Main Results:

• SC-XLMD accurately reproduced thermodynamic, dynamic, and structural properties.
• Simulations included bulk water and high-temperature RDX molecules.
• Demonstrated excellent computational performance compared to SCF methods.

Conclusions:

• The SC-XLMD method offers a computationally efficient alternative to SCF solvers.
• This new approach enhances the simulation of charge equilibration in molecular dynamics.
• The method is publicly available in the LAMMPS package for widespread adoption.