RESEARCH INTERESTS
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.

Currently, my group is working on several projects that are at the frontier of nano-scale science, which is becoming an uprising, emerging field for the next two decades. The essence of nano-scale physics lies in the importance of the size and shape of physical systems. It differs from macroscopic and even mesoscopic physics due to its ultra small scale. Quantum effects dominate the behavior of many processes. The discreteness of energy levels is reflected in most experimental measurements. Our goal is to understand the fundamental physics underlying observed properties and processes and to manipulate and predict outcome for future experiments.

Topics in my group includes phenomena at the metal-C60 interface [54,57], manipulation of charge transfer and band structure via metal atom-carbon nano-tube interactions [51,52], structure evolution and fragmentation pattern of silver oxide nano-crystals [50], spin-dependent transport properties of layered magnetic tunneling junctions [55], and structure-transport interplay of molecular electronics [56]. We have also studied water-silica interactions [46-48,53] and impurity states in the high temperature superconducting materials.

In the past, we have also worked on projects of: i), 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. For the 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.

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.


Group Members:

Postdoc:

Chao Cao   

Eric Wang   

Graduate Students:

Lex Kemper    Manoj Srivastave    Yun-Wen Chen    Yun-Ning Wu    Rashid Handam    Saha    Johnsson Chu    Xiao-Guo Li   

Undergraduate Student:

Former group members:

Mao-Hua Du, Ling-Ling Wang, Chun Zhang, Jian-Wei Zhang, Krishna, Muralidharan, Magnus Hedstrom, Ray Sadeghi, Andy Kolchin, Kyle Morrison, Christian Schlubac

Yao He    Luis Agapita    Lan Li Joey Nicely    


Collaborators

At UF: Professors Samual Trickey, Rodney Bartlett, Frank Harris, Erik Duemens, Jeffrey Krause, Adrian Roitber, Peter Hirschfeld, Jim Dufty, Andrew Rinzler, Art Hebard

Outside UF: Professors Catherine Brechgnac, Jerome Lengnier, Philip Cachuc, Drs. Jingguang Che, Xiao-Guang Zhang, Martin Schmitt