0000000000335821
AUTHOR
M. Presber
Phase Diagrams of Alloys and Adsorbed Monolayers: Some Recent Results
We discuss some recent work done on the calculation of phase diagrams of models of binary alloys and adsorbed monolayers. For the nearest-neighbor Ising antiferromagnet on the fcc lattice (model for the Cu-Au system) we study a rather large lattice of 4 x 643 spins. This is necessary since the inherent frustration of the lattice induces a very small interfacial tension between ordered domains. We find no indications for the suggested L′ phase, and locate the triple point at a nonzero temperature. There is some numerical evidence that it might in fact be a multicritical point. We then discuss the extension of lattice gas models to “elastic lattice gases” (ELGs) which include also translation…
Quantum simulations in materials science: molecular monolayers and crystals
Low temperature properties and anomalies in crystals and molecular monolayers are studied by path integral Monte Carlo (PIMC) simulations. For light particles (H 2 , D 2 ) adsorbed on graphite anomalies in the transition to the low temperature √3-phases have been observed in experiments and are analyzed by PIMC. The computed thermal expansion of various crystalline materials (Si, N 2 ) is in much better agreement with experiments compared to the results obtained with purely classical simulations.
Monte Carlo studies of adsorbed monolayers: Lattice-gas models with translational degrees of freedom
Standard lattice-gas models for the description of the phase behavior of adsorbed monolayers are generalized to ``elastic lattice gases'' which allow for translational degrees of freedom of the adsorbate atoms but have the substrate lattice structure built into the adsorbate-adsorbate interaction. For such models, we derive a simple and efficient grand-canonical Monte Carlo algorithm, which treats the occupied and empty sites in precisely the same way. Using this method, we calculate the phase diagram of a simple model for the adsorption of hydrogen on palladium (100); this model includes only pairwise interactions and exhibits an ordered $c(2\ifmmode\times\else\texttimes\fi{}2)$ structure.…