Hondenschool 101.
Welcome to the home-page of Gerard T. Barkema!
I am a senior researcher/lecturer (~assoc. prof.)
at the Institute for Theoretical Physics of the University of Utrecht.
My primary research area is computational physics, especially Monte
Carlo methods. I am actively developing new computational techniques,
and have applied these simulation techniques in a wide range of research
fields, mostly related to materials science, surface science,
statistical and polymer physics. In the last years, I have concentrated
on computer simulation of disordered materials,
especially amorphous semiconductors and dense polymer systems.
amorphous semiconductors
With a combination of several computational approaches, we are able to
generate well-relaxed sample configurations of amorphous semiconductors;
the techniques we use range from the so-called sillium
approach, introduced by Wooten, Winer and Weaire, through the
activation-relaxation technique introduced by Mousseau and me, to
first-principles calculations. The structural, electronic and optical
properties of our computer samples of amorphous silicon and gallium
arsenide agree well with experiment. They allow us to investigate a
range of topics, e.g. the nature of the dynamics (local vs. extended
events), and the relation between some properties of the Raman spectra
and the microscopic structure.
Here is an impression of how our samples (and hopefully also the real
material!) look like:
The long-term goal is to generate atomic configurations of a-Si solar
cells and complementary metal-oxide semiconductor (CMOS) devices. Such
"computer devices" allow the study of the effects that small structural
changes have on electronic and optical properties, and ultimately may be a
valuable tool to obtain improved device properties. The miniaturization
of electronic devices, in combination with the advance in computer
hardware and simulation methods, has brought in sight the possibility
to simulate electronic devices at the atomic level.
Within such devices, the electrically insulating oxide layers are
important, and therefore we also simulate silica at the atomic level.
A typical computer sample is depicted here:
dense polymer systems
The current theoretical understanding of the dynamics of dense polymer
systems is based on the pioneering work of de Gennes, centered around
the concept of "reptation": movement of a polymer by means of the
diffusion of stored length along the chain. To simulate the dynamics of
dense polymer systems, one cannot coarse-grain the polymers and at the
same time preserve the scaling properties of reptation. Our approach to
study the long-time and long-length dynamics of dense polymer systems
is to use a highly simplified description of the polymers ---lattice
polymers with nearest-neighbour interactions--- and very efficient
simulation techniques.
Some two-dimensional slices through a three-dimensional simulation of
a phase-separating polymer mixture are shown here:
And a little later:
Here is a list of my publications.