ON THE DYNAMIC EXPONENT OF THE 2-DIMENSIONAL ISING-MODEL

We use the method of 'damage spreading' to measure the time taken for the equilibrium damage (the magnetization) to disappear in finite systems (10 less-than-or-equal-to L less-than-or-equal-to 103) at the critical temperature of the infinite system. This time is found to scale as L(z) with an exponent z of 2.16 +/- 0.02. This value is compatible with the expected value of the dynamic exponent for the 2D Ising model, but we argue that this method is unable to measure fluctuations properly which we show are responsible for the higher values recently reported in the literature. We suggest that the slowest mode of relaxation has an exponent of z greater-than-or-equal-to 2.27.