DEVELOPMENT AND APPLICATION OF A REAXFF REACTIVE FORCE FIELD FOR HYDROGEN COMBUSTION

Open Access
Author:
Agrawalla, Satyam
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 26, 2010
Committee Members:
  • Prof Adri Van Duin, Thesis Advisor
  • Adrianus C Van Duin, Thesis Advisor
Keywords:
  • hydrogen combustion
  • ReaxFF
  • force field
  • reaction kinetics
Abstract:
To investigate the reaction kinetics of hydrogen combustion at high pressure and high temperature conditions, we constructed a ReaxFF training set to include reaction energies and transition states relevant to hydrogen combustion and optimized the ReaxFF force field parameters against training data obtained from Quantum Mechanical calculations and experimental values. The optimized ReaxFF potential functions were used to run NVT-MD simulations for various H2/O2 mixtures. We observed that the hydroperoxyl(HO2) radical plays a key role in the reaction kinetics at our input conditions (T≥2750K, P > 400atm). The reaction mechanism observed is in good agreement with predictions of existing kinetic models for hydrogen combustion. Since ReaxFF derives its parameters from quantum mechanical data and can simulate reaction pathways without any preconditioning, we believe that atomistic simulations through ReaxFF could be a useful tool in enhancing existing kinetic models for prediction of hydrogen combustion kinetics at high pressure and high temperature conditions, which otherwise is difficult to attain through experiments.