Our research is in the field of molecular modeling and simulation. More specifically, we are interested in developing and using molecular simulation methods, such as Monte Carlo methods, equilibrium and nonequilibrium molecular dynamics simulations, ab initio calculations, to analyze and understand the microscopic mechanisms underlying various nonequilibrium processes. Our recent research focuses on understanding and controlling polymorphism during crystallization. This is one of the long-standing challenges in solid-state chemistry. Polymorphism denotes the ability of a molecule to crystallize in more than one structure or packing arrangement. This phenomenon has broad practical implications for a number of industries, ranging from pharmaceuticals (drugs) to textiles (dyes and pigments) or defense (energetic materials). More generally, we develop an understanding of self-assembly on the nanoscale (studying the formation of metal and semiconductor nanoparticles or of systems of biological interest) and of transport on the nanoscale (studying the conductivity and viscosity of liquids confined in nanopores).

* Unraveling the interplay between thermodynamics and kinetics during the nucleation and growth of semiconductor, metal and molecular nanoparticles. Sponsor: NSF CAREER Award DMR-1052808 Collaborations: Prof. L. Yu, School of Pharmacy, University of Wisconsin-Madison       Prof. B. Garetz, Chemical and Biomolecular Engineering, NYU-Poly Because of their size, intermediate between the dimensions of atoms and of bulk matter, nanoscale materials often exhibit very unique properties. One needs, however, to be able to control the properties of nanomaterials, such as e.g. their crystalline structure, to fully harness the powerful properties of these materials. While physicists and synthetic chemists have developed many successful strategies to this end, a complete understanding of the molecular mechanisms underlying the formation of nanomaterials has remained elusive so far. The aim of our work is two-fold. Our first goal is to elucidate these mechanisms. For this purpose, we use simulation methods appropriate for the sampling of rare events (umbrella sampling, transition path sampling methods) to simulate the crystal nucleation process. Once the critical nucleus is obtained, we simulate its growth using conventional molecular dynamics simulations. Throughout nucleation and growth, using, and developing, when necessary, appropriate order parameters, we identify how and when the selection of a specific crystalline structure (or polymorph) takes place.