CPM Seminar

Amorphous materials represent a large class of the structures found around us. In spite of three decades of study, however, many fundamental questions regarding their structural, electronic, vibrational et dynamical properties are still open. With the help of many collaborators, I have been trying to answer some of these questions numerically. Our first goal was to generate models of quality comparable to that of experiment. This was achieved using the activation-relaxation technique (ART) and a modified Wooten-Winer-Weaire bond-switching algorithm. We can now prepare a-Si models of up to 40 000 atoms with a clean electronic gap in structural agreement with experiment. These techniques have also allowed us to study departures from the perfect randomness in a very controlled way, such as paracrystalline networks. Using ART, we have also been able to generate more than 20 000 activated events in a-Si, giving a first detailed picture of the dynamics of relaxation and diffusion in a disordered material. All these results, taken together, help us get a better picture of the basic properties of continuous random networks and of their relation to real materials.

Thursday, February 7th 2002, 16:00
Ernest Rutherford Physics Building, Keys Auditorium (room 112)