Johannes Roth, R. Schilling and H.-R. Trebin
The thermodynamic behaviour of mono- and diatomic models of threedimensional icosahedral quasicrystals has been studied in NVT and NPT ensembles using molecular dynamics simulations with atoms interacting via Lennard-Jones potentials. We also report on a microcanonical MD-simulation of decagonal Al65Cu20Co15 quasicrystals where an experimentally determined binary model has been used. To obtain stability in this latter case it is necessary to endow the atoms with effective pair potentials. No transitions to crystalline or amorphous phases were found for diatomic models. Monoatomic models, however, display a certain stability only in the low temperature region. In the range between 1/10 of the melting temperature T_M and T_M itself and in the high pressure range they decay to the fcc ground state of a LJ potential. A small region around the phase boundary is marginal: here the system abrupt changes its structure and finally also gets crystalline.