Research On Ground States Of Fcc Alloy Film

Ground states of alloy films are the basic knowledge to understand theorder-disorder transitions, growth and other characteristics of the films. Inthis paper, we calculate the structures and number of the ground states ofconfined binary alloy thin film by means of anneal simulation withMonte-Carlo method. In the computation, we just pay attention to the f.c.csystem, and use the Ising model with only the nearest-neighbor (NN) and nextnearest-neighbor (NNN) interaction. The ratio of NNN interaction and NNinteraction is set to be small. And we have found how the number of the thinfilm ground states varies with the change of layer number of the thin film.First, we propose some background knowledge for this thesis, andintroduce the specialty about the research. In the followed two chapters, theMonte-Carlo method are given and discussed. The simulation formulas andthe whole computation procedures are also been given.In the last chapter, we first give the calculated results of the film groundstates for the case that the ratio of NNN interaction and NN interaction isnegative, which includes the number, structures, the Hamilton analyses andphase-diagram of ground states. We can reach the conclusion: The number ofeven layer thin film ground states increase with the layer number, it reachesthe maximum value 25 when layers number is 8 and does not change whenlayer number is larger;the numbers of odd layer thin film ground statesincrease with the layer number, it reaches the maximum value 15 when layernumber is 5 and does not change when layer number is larger. We haveanalyzed how the anti-phase boundary affects the ground states of the films.We also obtain the results of the odd layer films for the ratio of NNNinteraction and NN interaction is positive: The numbers of odd layer thin filmground states increase with the layer number;it reaches the maximum value79 when layers number is 11. Then the counts of the film ground statedecrease with the layer numbers, it reaches constant value 73 when layernumber is 15 and remain 73 when the layer numbers are larger than 15.