Gluing potential energy surfaces with rare event simulations.

Area of Science:

• Computational chemistry
• Molecular dynamics simulations
• Quantum mechanics/molecular mechanics (QM/MM)

Background:

• Accurate molecular simulations require high-level quantum mechanics, which is computationally expensive.
• Classical molecular dynamics (MD) is efficient but lacks accuracy for bond-breaking/forming events.
• Bridging these methods is crucial for simulating complex chemical processes.

Purpose of the Study:

• To develop a novel computational method that integrates classical and quantum mechanical simulations.
• To enable accurate modeling of chemical reactions within a larger molecular system.
• To create a dynamical QM/MM approach for time-domain simulations.

Main Methods:

• Developed a new method, QuanTIS (Quantum Transition Interface Sampling).
• Combines replica exchange transition interface sampling with two distinct potential energy surfaces.
• Integrates density functional theory (DFT) based MD with classical force fields.

Main Results:

• Successfully applied QuanTIS to model an ion dissociation reaction and a classical hydrogen model.
• Demonstrated the method's capability to handle bond breaking and formation accurately.
• Showcased the ability to simulate diffusion in solvents using classical force fields concurrently.

Conclusions:

• QuanTIS offers a computationally efficient way to perform accurate molecular dynamics simulations of chemical reactions.
• The method bridges the gap between classical and ab initio dynamics in the time domain.
• Potential for on-the-fly optimization of classical force field parameters for chemical reactions.