A Multipole-Based Reactive Force Field for Hydrocarbons.

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Physics

Background:

• Quantum chemistry methods are computationally expensive for large-scale reactive systems.
• Existing reactive force fields rely on complex, knowledge-based corrections, hindering development.
• Need for accurate and efficient models for molecular dynamics simulations of chemical reactions.

Purpose of the Study:

• Introduce a novel atomic multipole-based reactive model with bond free (OPERATOR).
• Develop a physically motivated, simplified force field within the AMOEBA framework.
• Improve the description of electrostatic interactions and chemical environments during reactions.

Main Methods:

• Constructed OPERATOR force field using a physically motivated model within the AMOEBA framework.
• Dynamically generated atomic multipoles to capture environmental changes during reactions.
• Incorporated charge penetration, polarization, charge transfer, van der Waals, and three-body potentials.
• Optimized using DFT-derived potential energy surfaces (PESs) of hydrocarbons across millions of conformations.

Main Results:

• The OPERATOR force field accurately replicates atomic monopoles and energies.
• Demonstrated comparable or superior performance against the ReaxFF reactive force field.
• Molecular dynamics simulations of n-heptane decomposition successfully reproduced experimental products and reactions.

Conclusions:

• The OPERATOR force field offers a simplified, physically grounded approach to modeling chemical reactions.
• Its ability to capture dynamic electrostatic changes is crucial for reactive simulations.
• Expected to facilitate future investigations into complex chemical reaction mechanisms across various elements.