Development of a Charge-Implicit ReaxFF for C/H/O Systems

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Physics

Background:

• Modeling condensed-phase chemical reactions is computationally challenging.
• Existing ReaxFF force fields offer accuracy but suffer from slow simulation speeds due to algorithms like charge equilibration.

Purpose of the Study:

• To develop a faster, charge-implicit ReaxFF force field (ReaxFF-CHO) for modeling carbon, hydrogen, and oxygen systems.
• To investigate the mechanism behind enhanced secondary ion mass spectrometry sensitivity observed during trehalose bombardment by water clusters.

Main Methods:

• Reparameterization of ReaxFF to incorporate Coulomb forces into other force field terms, creating a charge-implicit model.
• Simulation of trehalose bombarded by water clusters using the novel ReaxFF-CHO potential.

Main Results:

• The charge-implicit ReaxFF-CHO model achieves over two times the simulation speed of the original ReaxFF.
• The potential accurately models reactions and densities for systems containing carbon, hydrogen, and oxygen.
• Simulations revealed that increased secondary ion mass spectrometry signal intensity correlates with the emission of trehalose-water complexes.

Conclusions:

• The developed ReaxFF-CHO force field offers a significant speedup for condensed-phase reaction modeling without sacrificing accuracy for C, H, and O systems.
• The simulations provide a mechanistic explanation for experimental observations in secondary ion mass spectrometry, linking signal enhancement to the formation of molecular complexes.