W e present the results of a molecular-dynamics study on a LennardJones mixture.Measurements of density and bond-angle correlation functions show that the answer to the question posed in the title is NO. We also show that icosahedral order plays no special role in the glass transition, but that a normalized measure of the persistence of orientational correlations in the glass shows a systematic dependence on the spherical harmonic index 1.
Novel computer simulations are described of the time evolution of an ordering model binary alloy following quenching from a disordered state at a high temperature. The results are interpreted with use of ideas of Lifshitz and of Cahn and Allen; the ordering process is described by a kinetic equation for the motion of the walls separating domains with different orderings. The characteristic length increases as t 1 ' 2 , and the structure function scales as kt i/2 .
We have studied the compressible antiferromagnetic Ising Model on a triangular lattice using Monte Carlo simulations. It is found that the coupling to the strain removes the frustration of the rigid model and the simulations show a transition from the disordered to an ordered, striped phase at low temperatures. This transition involves two broken symmetries: the Ising symmetry and a three-state Potts symmetry characteristic of the triangular lattice. In the absence of bond fluctuations, this transition is always strongly first order. Using finite-size scaling analysis, we find evidence that, in the presence of fluctuations, the transition becomes weakly first order and possibly second order when the coupling to the lattice is increased. We discuss the relevance of this model to certain phase transitions in alloys. ͓S0163-1829͑96͒04918-1͔
e have investigated, via Monte Carlo computations, the phase diagram of an ordering binary alloyequivalent to an Ising spin systemon an fcc lattice with nearestand nextnearest-neighbor pair interactions X =J X""o, tr&al X"""o;oi,o; =+ 1, J )0. Our studies indicate that this system undergoes a first-order transition; i.e. , there is a discontinuity in the energy and order parameters as a function of temperature, for values -1 & e & 0.25. For larger values of~o~the transition appears to be continuous, without any metastabie states. Our results are in good agreement with Kikucki's cluster variation method at the two values of n at which it has been applied, namely, 0 and -0.25. For e ( -0.5 renormalization-group arguments strongly indicate that the transition is first order. If this is so, then our results indicate that the discontinuities for a & -1 must be very small. The nature of the ground states changes at o. =0 and -0.5. At these values of a the ground states are infinitely degenerate.The structure of the low-temperature phases, at all values of u, is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.