DEPARTMENT
OF PHYSICS & ASTRONOMY
Theoretical Physics
Atomic & Molecular Physics
Jogindra M. Wadehra
The emphasis of our work is on studying the scattering of positrons
(antiparticles of electrons) and electrons from various atoms and
molecules. The systems under current investigation include rare gas
atoms, alkali atoms and light molecules. We have also calculated and
compared the cross sections for the ionization of inner shells of
various atoms by impact of both positrons and electrons.
Other research interests include investigations of production of
negative ions by the process of dissociative electron attachment to
simple molecules. The rates of negative ion production by this process
are strongly enhanced if the attaching molecule is initially
rovibrationally excited. We have also calculated the cross sections for
the vibrational excitation and dissociation of simple molecules by
electron impact. Atomic and molecular collision processes play
important and significant roles in astronomy and astrophysics.
Caroline G. Morgan
The nature of the atomic-scale defects in semiconductors often
determines the optical, electronic, and structural properties of these
materials, and how these properties change with time, heating,
pressure, and application of fields. Our research group investigates
the properties of the important defects and defect complexes occurring
in various semiconductors. In order to be able to identify the
defects responsible for particular experimental properties (and suggest
how to optimize these properties as desired for particular
applications), we use first-principles quantum molecular dynamics
calculations to search for low energy defect structures, characterize
the electronic and optical properties of these low-energy defects, and
compare these properties with the experimental observations. We
also determine whether these energetically favorable defects have
metastable higher energy configurations, and investigate their motion
and interactions. Since these calculations are very
demanding, they are supported by grants of supercomputing time from the
Air Force Office of Scientific Research at ERDC, NAVO, and other
national supercomputing centers.
There is currently a lot of interest in producing nanoscale devices and
low-dimensional structures, such as quantum dots, in order to achieve
faster response times, and the possibility of modifying the properties
as desired by changing the geometrical dimensions. While changing
the conditions during growth and processing can affect the quality of
surfaces and interfaces and the concentrations of various defects
remaining in important regions in larger devices as well, this can
produce particularly dramatic changes in the properties of
low-dimensional or very small structures. Therefore a better
understanding of semiconductor growth at the atomic level is needed.
Our research group is currently investigating how growth and processing
under different conditions can lead to different concentrations of
structural defects at the surface, and different concentrations of
various defects remaining in the material after growth. In order
to address these questions, we use first-principles calculations to
study the dynamics and energetics of the microscopic processes
occurring at the growing semiconductor surfaces, as well as the defects
which can occur at the growing surface.
References and an overview of some of the first-principles methods we
use, including codes written and maintained by our long-term
collaborators at the Fritz-Haber-Institut der Max-Planck-Gesellschaft
and a manual on how to do these calculations coauthored by us, is
available at http://www.fhi-berlin.mpg.de/th/fhi98md/.
Some recent publications:
“First-Principles Study of As Interstitials in GaAs: Convergence,
Relaxation, and Formation Energy”,
J. T. Schick, C. G. Morgan, and P. Papoulias, Physical Review B66
195302 (2002).
“Optical and Electrical Properties of Low to Highly Degenerate InN
Films”, D. B. Haddad et al., Mat Res. Soc. Symp. Proc. 798
Y12.7.1-Y12.7.6 (2004).
Jhy-Jiun Chang
Theoretical
studies concentrate on understanding the microwave responses of layered
superconductors and the physics of the dynamic states arising from the
Josephson
tunneling in these layered superconductors.
A. Petrov, W. Rolnick, F. Gabbiani, and J. Tandean
The aim of theoretical high energy physics is to seek and
understand the universal laws of Nature. The major thrust of research
pursued by the Wayne State University particle theory group lead by
Prof. Alexey Petrov is the issues pertaining to the understanding of
the structure of the fundamental electroweak Lagrangian at the smallest
scales and development of the theoretical tools needed for “clean”
interpretation of the experiments designed to answer such fundamental
questions as the origins of mass and CP-violation.
Given the complicated dynamics of strong interactions, the
interpretation of experimental observables in terms of fundamental
parameters is often complicated, which makes the study of the strong
interaction effects absolutely crucial. In this regard, the promise of
heavy quark states is that these effects can be studied systematically
by exploiting symmetries arising in the limit of infinite mass of the
heavy quark. The existence of the large scale associated with the mass
of the heavy quark also allows for development of efficient and
controllable approximations leading to significant reduction of
theoretical uncertainties. The underlying theme behind all aspects of
the group’s work is the application of quantum field theory to the
problems of particle phenomenology. In recent years the group has
worked on a variety of problems in the theory and phenomenology of the
strong, electromagnetic, and weak interactions. A partial list of
research topics includes studies of the properties of heavy hadrons,
applications of effective field theories to problems in Quantum
Chromodynamics (QCD), meson spectroscopy, and physics of CP-violation.
The group is also one of the leaders world wide in the description of
weak transitions of charmed hadrons. The research program of WSU’s
particle theory group has significant overlap with current research
interests of the Wayne State experimental particle physics groups.
These activities are supported by grants from the U.S. National Science
Foundation and Department of Energy.
For more information see http://www.physics.wayne.edu/~apetrov/particle_nuclear/
S. Gavin
Theoretical high-energy nuclear research lead by Sean Gavin brings
cutting edge theoretical techniques to bear on the dynamics of the
quark-gluon plasma and relativistic heavy ion collisions. Gavin’s
research has touched almost every problem in this active field. Best
known for his work on charmonium production, he has done highly cited
and important work on several very different problems in this field,
including thermalization, disoriented chiral condensates, parton energy
loss, HBT and correlations. Methods he has used include quantum field
theory, QCD perturbation theory, and nonequilibrium statistical
mechanics. Computational methods range from pencil-and paper to
numerical simulations on our 20 CPU Linux array. In the last three
years he guided and supported the research of five graduate students,
leading to one completed PhD as of 2004. These efforts are supported in
part by a U.S. National Science foundation CAREER award.
Alvin M. Saperstein
Studies of interacting systems and their stability. Specifically,
the application of the mathematical concepts of recursive
relations, chaos, and complexity, to the system of armed competing
states. The goal is to attain insight into how to make international
security
policy-what choices will lead to dangerous international instability
and the
probability of war.