Recent Work
For the past few years, I have been a postdoctoral researcher at
Columbia University working in the group of
Professor Bruce Berne. In this capacity, I have studied a broad
range of problems. One focus of my postdoctoral research has been
the development and extension of multiple time scale (MTS)
molecular dynamics techniques. Multiple time scale techniques
facilitate computationally efficient simulation as expensive long
range interactions are updated less frequently than more rapidly
varying intramolecular forces. This work began with the
recognition that there are pitfalls associated with MTS
integrators. We discovered that proper conservation of energy
depends on carefully designing a suitably smooth function
that switches between short-range and long-range
interactions. 
We next developed
techniques that alleviate resonance instabilities in MTS
integrators. Such instabilities engender a spurious transfer of
energy from high frequency to low frequency modes and limit the
efficiency of the algorithm. We found that recently developed
colored noise thermostats may be designed to correct such
instabilities while only minimally perturbing the system's
dynamics. In this way, more computationally intensive long-range
interactions can be evaluated less frequently, thereby
facilitating more efficient simulations.
Recently, we have studied how hydrodynamic interactions impact hydrophobic assembly. Within the framework of Brownian dynamics, we uncovered the interplay between the free energy surface and the frictional force that is engendered by hydrodynamic interactions as two nanoscopic bodies approach each other. In addition, we have explored the impact of nuclear quantum effects on glass formation. We discovered reentrant behavior in the liqud-glass phase diagram as the magnitude of nuclear quantum effects are increased. Weakly quantum bodies behave as if they have a larger effective radius and therefore exhibit a greater propensity for glass formation. For larger degrees of ''quantumness,'' tunneling and zero motion facilitate movement. This is illustrated by the figure above.
Nuclear quantum effects in water
Previously, I was a graduate student in the Department of Chemistry at Princeton University. I was a member of Roberto Car's research group, and I completed my doctorate in July 2008.
This work was centered upon the further development of path integral simulation methodology. Path integral simulations are used in order to describe nuclear quantum effects. Typically in molecular simulation, the nuclei are treated as classical point particles. Nuclear quantum effects are particularly important in the description of hydrogen, since it is the lightest atom and particles tend to behave more ''quantum'' as their mass and temperature decrease. Therefore, nuclear quantum effects can be essential for the understanding of hydrogen-bonding and proton transfer.
To the right is a snapshot of a path integral simulation of water. 
Each set of overlapping ''classical'' water molecule coordinates represents one water molecule as described by quantum mechanics. It is quite beautiful that such a simple picture falls out of certain approximations that one can make to the fundamental equations of nature.
There were two primary goals for my work in this area. The first was the development of higher-order path integral algorithms that can both increase the efficiency of the computation, and be utilized to study hydrogen-bonding molecular systems such as water. Some promising (albeit preliminary and incomplete) results were garnered, and are reported in my dissertation.
Secondly, I was involved in the development of algorithms to compute the proton momentum distribution, which utilize a so-called ''open'' path integral approach. To this end, we have developed an algorithm for ''open'' path integral simulation. This method was first shown to work in conjunction with an empirical potential-based model of water. This methodology has also been implemented in conjunction with first principles (Car-Parrinello) molecular dynamics. First principles open path integral molecular dynamics simulations have been carried out utilizing IBM Blue Gene/L hardware. We have carried out these studies on a variety of phases of water. Please see my dissertation and the work with Roberto Car that is listed in the references for more information.
Proton transfer in hydrogen bonding liquids
I also worked under Mark Tuckerman in the Chemistry department at New York University as an undergraduate researcher. 
There, I spent three years learning the ropes of Car-Parrinello molecular dynamics, and applying these methods to study proton transport. In the course of my research, we proposed a mechanism for proton transfer in methanol and methanol-water mixtures. Additionally, we created a novel QM/MM (quantum mechanical / molecular mechanical) potential for the methanol. The figure shown to the the right is a snapshot of a configuration of a molecular dynamics simulation of protonated methanol. The ions and molecules depicted as larger spheres are members of the 'defect chain,' that is the species along which proton conduction occurs.