Research interests: theory of condensed matter (the liquid and solid phases of materials), and includes computer simulations of these condensed phases. Of particular interest to Tony are those states that are associated with monolayer films of atoms of one type adsorbed on the surface of a crystal of another type. A related problem of some interest is the reconstruction of surfaces. These systems are predominantly two-dimensional (rather than three-dimensional) and so show rather interesting and uncommon phenomena. The problems of interest are those that examine the structure of the phases of these systems and the nature of the phase transitions.
Incommensurate solids, those which possess some aperiodic structure that does not reflect the fundamental periodicity of the parent crystal structure, pose another very interesting class of problems. Since the natural periodicity of the monolayer is usually different from that of the surface on which it lies, monolayer systems often form incommensurate structures due to the competing forces of the intra-monolayer interactions and the interactions of the monolayer with the surface. Sometimes the periodicity of the parent crystal can be partially recovered, and this leads to the so-called commensurate phases. Another part of Tony’s research program is the study of the structure of both the commensurate and incommensurate phases and of the phase transitions between them.
One of the more interesting problems in condensed matter physics is that of the melting of a solid in two dimensions. The main question is whether the melting occurs through a discontinuous transition as it does in bulk (three-dimensional) systems, or whether this melting occurs via a continuous transition, very different from bulk systems. Tony is approaching this problem through computer simulations.
Tony’s work has been funded by research grants from the National Science Foundation, and he maintains contact with experimental groups at Brookhaven National Laboratory, Exxon Corporate Research Center, and the University of Washington at Seattle to foster the kind of interaction between theory and experiment needed for a healthy research program. Students have been involved with Tony’s research on a number of occasions in the past, and he has supervised recent honors theses on computer simulations of monolayer melting, adsorption of quantum solids, and deterministic chaos. Chiyu Chen ’09 worked as an EXCEL Scholar with Tony during summer 2008.