Shunda Chen, Yong Zhang, Jiao Wang, Hong Zhao
We study the finite-size effect in calculating the autocorrelation function of the global flux using periodic boundary conditions in this Letter. By studying the spatiotemporal correlation of the local flux, it is shown that the size effect is induced by the interaction of the sound modes. A local-flux fluctuation may excite sound modes spreading outwards with a speed v, and interaction may take place when they meet due to the finite size of simulation domain. As a consequence, we conclude that one could only correctly extract the correlation function using a periodic domain of L for a time period of t < L/(2v). This criterion implies that a lot of previous works related to the numerical simulation of the correlation function need to be rechecked.
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http://arxiv.org/abs/1208.0888
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