Reaction Ensemble Monte Carlo Simulation of Complex Molecular Systems

Area of Science:

• Chemical Physics
• Computational Chemistry
• Molecular Modeling

Background:

• Reaction ensemble Monte Carlo (RxMC) simulations are crucial for modeling chemical reactions at the molecular level.
• Accurate acceptance rules are essential for the reliability of RxMC simulations, especially for complex systems.
• Existing methods for molecule insertion/deletion in RxMC can be computationally intensive.

Purpose of the Study:

• To derive and present new acceptance rules for RxMC simulations incorporating atomistic degrees of freedom.
• To implement a gradual insertion/deletion method using the continuous fractional component (CFC) approach.
• To validate the new method against established systems and identify sources of discrepancies in previous studies.

Main Methods:

• Development of novel acceptance rules for RxMC simulations with gradual molecule insertion/deletion via the CFC method.
• Self-consistent utilization of ideal gas free energy parameters within RxMC moves.
• Application and testing of the method on propene metathesis and methyl-tert-butyl-ether (MTBE) synthesis reactions.

Main Results:

• Quantitative agreement achieved for propene metathesis reaction with prior work (Keil et al.).
• Identified an incorrect Monte Carlo acceptance rule formulation as the cause for discrepancies in MTBE synthesis equilibrium concentrations (vs. Lísal et al.).
• Demonstrated efficiency gains of the CFC method over single-stage molecule insertions in Monte Carlo simulations.

Conclusions:

• The developed CFC-based RxMC method provides accurate and efficient simulations for complex molecular systems.
• The study highlights the critical importance of correct acceptance rule formulation in RxMC simulations.
• The findings offer a more reliable approach for predicting chemical equilibrium concentrations and reaction dynamics.