A minimal implementation of the AMBER-GAUSSIAN interface for ab initio QM/MM-MD simulation

Area of Science:

• Computational Chemistry
• Molecular Dynamics
• Quantum Mechanics/Molecular Mechanics (QM/MM)

Background:

• Accurate simulation of molecular systems requires integrating quantum mechanics (QM) for reactive centers and molecular mechanics (MM) for the environment.
• Existing QM/MM methods often involve complex interfaces and modifications to established simulation packages.

Purpose of the Study:

• To develop a straightforward interface (AG-IF) connecting AMBER and GAUSSIAN for QM/MM molecular dynamics simulations.
• To facilitate the application of advanced theoretical methodologies in computational chemistry.

Main Methods:

• Developed an AMBER-GAUSSIAN interface (AG-IF) with minimal modifications to existing AMBER and GAUSSIAN software.
• Implemented a novel approach for calculating electrostatic forces between MM and QM regions.
• Utilized the AG-IF for QM/MM molecular dynamics simulations.

Main Results:

• The AG-IF allows retrieval of QM/MM energy and forces from GAUSSIAN for AMBER's Newtonian dynamics solver.
• Demonstrated the interface's utility through three applications: QM vs. MM radial distribution function, free energy gradients, and charge calculations.
• The minimal implementation requires only AMBER modification, leaving GAUSSIAN unchanged.

Conclusions:

• The AG-IF provides a simple and adaptable platform for QM/MM molecular dynamics.
• The developed interface enables efficient application of theoretical methodologies for complex molecular simulations.
• The demonstrated applications highlight the AG-IF's potential for advancing computational chemistry research.