UC Berkeley, Bachelor in Physics

Research Project

Force Matching

Molecular mechanics is a widely used simulation technique where atoms and molecules move classically according to Newton's Laws and the potential energy is a parametric function of the nuclear positions. The classical potential energy function, called a force field, is composed of functional forms and empirical parameters chosen such that the simulation accurately represents the physical molecules. The utility of molecular mechanics depends critically on the accuracy of the force fields used, and force field development is an active field in theoretical and computational chemistry.

There are several strategies for parameterizing a force field. One may choose parameters to reproduce a target set of experimental properties, which has the advantage of accurately reproducing these target properties by design but often fails to describe other aspects of the system. Another approach, known as force matching, consists of first computing a training set of energies and forces from a higher-accuracy and higher-cost method (e.g. density functional theory), and then finding the optimal force field parameters to match these energies and forces.

I have developed ForceBalance, a force matching program written in Python and coupled to a customized version of GROMACS, which performs force matching for a wide variety of force field functional forms. My research project includes improving upon force matching methods, especially in the sampling of training data. I have also applied ForceBalance to compute polarizability parameters for fluctuating-charge force fields.

Source Code for ForTune force matching program

Water Oxidation

The oxidative half-reaction of water splitting (2H2O -> O2 + 4H+ + 4e-) is a thermodynamically demanding, mechanistically complex reaction with important implications for our future energy economy. In the last couple of decades, a number of molecular catalysts have been discovered that lower the overpotential for the water oxidation reaction, and this has generated much interest in the details of the water oxidation mechanism.

My project consists of using theoretical methods (DFT, solvation models, QM/MM) to accurately describe these water oxidation catalysts, with the goal of understanding the water oxidation mechanism in various systems.

Page last modified on February 24, 2013, at 04:15 PM