Title: Local surface structure and composition evolution by Monte Carlo simulations
1Local surface structure and composition evolution
by Monte Carlo simulations
Jiebing Sun1, James B. Hannon2, Gary L. Kellogg3,
Karsten Pohl1 1 University of New Hampshire,
Department of Physics, NH 2 T. J. Watson
Research Center, IBM Research Division, NY 3
Sandia National Laboratories, Albuquerque, NM
2Monte Carlo method
- Cu-Pd NN bonds favorable
- A trial move involves swap of element identities
- Free parameters ? --- NN Cu-Pd bond energy
- ? --- chemical
potential - Internal energy En?, where n is the total number
of NN PdCu bonds
3Terrace concentration over time
- Constant-NVT simulation
- Adjust ? to get best fit of simulation with
experimental data in c1 and c2 to get ?? 25 meV
4Heterogeneity across a step
- Thermo-dynamical integration method
- Entropy S integrating dQ/T with respect
to temperature and using Boltzmann formula
SklnW at high temperature - Chemical potential ? ?F/ ?N ?E/ ?N -
T?S/ ?N. - Constant- ? VT method
- Surface region open to a reservoir to
allow Cu-Pd exchange
5Chemical potential ? by two methods above
6Heterogeneity near a step
- ?? 25 meV
- Nearly constant chemical potential along each
single scan line - c1 and c2 agree with the experimental data
J. Sun, J. B. Hannon, K. Pohl, G. L. Kellogg, PRB
(in production)
7A case
- c3 and c1c2 fixed
- compute partition of c1 and c2
- c3 0.33
- c1c2 0.58
- ?? - 25 meV