Research
Thrusts
.... .Nanostructures
.... .Biomimetics
..... Bio-Nano
Hai Ping Cheng - My research aims at development and application of computer-based theoretical methodologies for investigation of physical problems in complex systems. The goal is to develop a basic understanding of physical and chemical properties of atomic and molecular clusters. These systems exhibit unique properties because of their finite size, and therefore are of great fundamental significance as well as technological value. We have been working on, and plan to continue, systematic investigations of size-dependent energetic, structural, dynamic, and thermodynamic properties of various clusters, the interaction between clusters and the surface of bulk matter, and the transition from the atomic and molecular regime to the condensed phase. In the last four years, we have focused on two major projects: i), the structure and dynamics of water clusters and ii) particle-surface interactions.
The first project concerns the structure and dynamics of water clusters. We studied protonation of clusters, proton transfer, and ion-water interactions using the state-of-the-art, first-principles molecular dynamics (MD) methods. These studies identified the fundamental characteristic frequencies of proton motion at various temperatures and the growth patterns of hydrogen-bonded networks in aqueous clusters. The project also the resulted in development of a new theory of two-center solvation shell structure, based on the results of the simulations. Currently We are extending these investigations to systems that are related directly to contemporary environmental and biophysical issues.
The second project concerns particle-surface interactions. We have been developing simulation models that include electronic degrees of freedom in an empirical manner as a significant extension of standard MD methods. These models have enabled studies of Coulomb explosions and bond-breaking caused by the interaction of highly charged ions (HCI) with surfaces. Thus, we have investigated the dynamics and thermodynamics of physical processes that occur under extreme conditions. Transient states, nano-structure formation, and shock wave propagation during nano-scale explosions were discovered and fully characterized in these studies. This work is in collaboration with an experimental group at the National Institute of Standards and Technology. Recently, my group has become involved in two new projects: manipulation of clusters on surfaces and photo-luminescence of spark-processed Si. Visualization has always been an necessary component of my research activities to analyze large amount of data generated in simulations. In collaboration with a colleague Jeff L. Krause, we established the quantum Visualization Studio (QVS) at QTP. This studio is designed to produces high quality scientific images and animations. We aim to develop visualization as a tool for scientific research, efficient communication, and modern education.