Pierre A. Deymier

Ph.D., Massachusetts Institute of Technology
Associate Dept. Head and Professor
The University of Arizona
The Department of Materials Science and Engineering
Mines Bldg., Room 125E
Tucson, AZ 85721
Phone: (520) 621-6080
e-mail:deymier@email.arizona.edu

Teaching Interests:

• Thermodynamics
• Imperfections
• Computer Simulation Techniques
• Scientific Visualization and Virtual Reality

Current Research:

• Calculation of transport properties of metal alloys
  Modeling and simulation of solidificaiton processes in metallic alloys requires the knowledge of transport properties (viscosity and diffusion coefficient) as a funciton of density, composition and temperature. Experimental measurements of these properties are difficult and often result in a lot of scattering in the data. In addition the data base is quite sparse. Molecular dynamics simulation methods (equilibrium and non-equilibrium) in combination with realistic Embedded Atom Models for FCC metals is used to provide a reliable and cheap way of calculating the transport properties of pure metals and binary alloys.
• Modeling and simulation of materials with strongly correlated electrons.
  Electron-electron interactions play a critical role in the behavior of many condensed matter systems including high-temperature superconductivity in cuprates. We have developed a molecular dynamics method based on the restricted path integral representation of quantum particles to simulate strongly correlated electron systems. Current applications are on electron plasma and alkali metals. In particular our current interest focuses on the metal-insulator transition (Mott's transition) in expended liquid and solid monovalent metals and in particular antiferomagnetic ordering.
  Future research will concentrate on the behavior of correlated electrons in conducting ceramic oxides.
• Post Chemical-mechanical polishing (CMP) cleaning of wafers with megasonic waves
  Megasonic cleaning is commonly used in post CMP processing although the mechanism for removal of contaminant particles by the sonic wave is not understood. With this method contaminated wafers are immersed in an aqueous solution and subjected to a high power acoustic beam with frequenxy ~ MHz. We are using the Green's function based Interface Response Theory (IRT) to calculate the interaction between acoustic waves and patterned or planar wafers. The models include the effect of ciscosity of the fluid and allow for the calculation of acoustic pressure fields as well as acoustic streaming (the time independent flow of fluid resulting from the pressure field). Calculated cleaning forces are compared with adhesion forces of contaminant particles and wafer.
• Electromagnetic/acoustic/electronic/magnetic band gaps in composite materials
  The propagatoin of physical excitations such as electromagnetic, acoustic, electronic and magnetic waves in composite materials is investigated. The focus is on the existence of band gaps for these excitations and the relation between the gap width and location with the geometrical and physical characteristics of the composite medium. Up to date we have concentrated on periodic one-dimensional and two-dimensional composite systems. The one-dimensional systems are networks of one-dimensional wave-guides such as comb or ladder structures. The two-dimensional systems are fiber composites with aligned fibers. This research uses the IRT as well as the plan wave method in calculating the band structure of periodic composite systems. Experimental measurement (essentially for acoustic band gaps have been conducted to confirm the theoretical prediction of acoustic gaps in composites). We have had some interest in wave propagation in non-periodic and disordered systems but this part of the research is still in its infancy.
• Interfaces and Grain Boundaries
  I have studied the structure and properties of interfaces and grain boundaries for quite some time using molecular synamics and electron microscopy. I have been involved in the study of grain boundary phase equilibria as well as the phenomenon of segregation at interfaces. The most recent focus of my work in this area is on quaiperiodic grain boundaries. These interfaces exhibit no periodicity but possess long range order. They are the two-dimensional equivalent of quasicrystals. This work at the moment involves essentially high-resolution electron microscopy (HREM) of the family of 45 twist grain boundaries in Al.
• Grain growth
  I have interests in implementing a molecular dynamics simulation of two-dimensional sub-micron to micron size systems to investigate two-dimensional grain growth. My interest is in the growth kinetics of anisotrophic systems and the interplay between length scales. The growth kinetics of anisotropic systems is expected to have a smaller correlation length between grains with similar orientation. We have recently used two-dimensional wavelets analysis to quantify the length scales and correlation in growing microstructures.
• Other Interests:
• Applications of the thermodynamics of stressed solids
• CMP
• MD simulation of suspensions of solid particles in fluids
• Other types of quantum molecular dynamics: DFT-MD, Tight-binding MD,...
• Materials modeling and simulations in general

Principal Publications:

• J.O. Vasseur, B. Djafari-Rauhani, L. Dobrzynski, and P.A. Deymier, "Acoustic band gaps in fibre composite materials of Boron-Nitride structure,: J. of Physics; Condensed Matter, 9, 7327 (1997).
• C.Y. Lee and P.A. Deymier, "Two-electron States in Ba_0.6K_0.4BiO₃ via Discretized Path Integral Molecular Dynamics," Solid State Communications, 102, 653 (1997).
• J.O. Vasseur, P.A. Deymier, l. Dobrzynski, B. Djafari-Rouhani, and A. Akjacy, "Absolute band gaps and electromagnetic transmissions in quasi-one-dimensional comb structures,"Phys. Rev. B, 55, 10434 (1997).
• J.O. Vasseur and P.A. Deymier, "Propagation of Acoustic Waves in Periodic and Random Two-Dimensional Composite Media," J. Mat. Res. , 12, 2207 (1997).
• P.A. Deymeir, J.O. Vasseur and L. Dobrzynski, "Anomalous Exponent in the Kinetics of Grain Growth and Anisotropic Interfacial Energy," Phys. Rev. B, 55, 1 (1997).
• M. Shamsuzzoha, P.A. Deymier and D.J. Smith, "An HREM Strudy lof a 45<>twist Quasiperiodic Grain Boundary in Aluminum," Scripta Mater., 35, p. 327-331 (1996).
• P.A. Deymier, G.E. Jabbour, J.D. Weinberg and F.J. Cherne, "Electronic and Atomic Structure of Liquid Potassium Via Path Integral Molecular Dynamics with Non-Local Quantum Exchange," Modelling and Simulation in MSE, 4. p. 137-150 (1996).