Hm. Polatoglou et Gl. Bleris, COMPARISON OF THE CONSTRAINED AND UNCONSTRAINED MONTE-CARLO METHOD - THE CASE OF CU3AU, Solid state communications, 90(7), 1994, pp. 425-430
The order-disorder transition of Cu3Au is studied using the constraine
d and unconstrained (constant temperature and pressure) method. Two co
nstrains are applied, namely the constant volume and the fixed atomic
positions. A N-body potential is utilized determined from the zero tem
perature structural properties of fcc Au, Cu and Cu3Au. The transition
temperature determined using the present potential and the constraine
d Monte-Carlo method agrees well with the experimental one. Releasing
the constant volume constrain we obtain a charge in the lattice consta
nt at the transition temperature which is twice as large as the experi
mental data indicate. The unconstrained Monte-Carlo method predicts ve
ry well the change of the lattice constant and the mean-square displac
ement at the order-disorder transition. Only the transition temperatur
e is found to be 25 % lower. The results indicate that the relaxation
effects and the chemical effects are properly accounted by the N-body
potential.