Direct Determination of the Probability Distribution for the Spin-Glass Order Parameter

The recent interpretation of Parisi's order-parameter function q (x) in terms of a probability distribution for the overlap between magnetizations in different phases is investigated by Monte Carlo computer simulation for the infinite-range Ising spin-glass model. The main features of the solution for q (x) are reproduced, in particular q (x) as x0 and q^' (x) =0 at q=q₌₀ₗ, the largest value. Finite-size effects prevent one from establishing with certainty whether there is a "plateau, " i. e. , q^' (x) =0 for a range of x.