Kosov D S, Gelin M F, Vdovin A I
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Feb;77(2 Pt 1):021120. doi: 10.1103/PhysRevE.77.021120. Epub 2008 Feb 25.
Grand canonical and canonical ensembles become equivalent in the thermodynamic limit, but when the system size is finite the results obtained in the two ensembles deviate from each other. In many important cases, the canonical ensemble provides an appropriate physical description but it is often much easier to perform the calculations in the corresponding grand canonical ensemble. We present a method to compute averages in the canonical ensemble based on calculations of the expectation values in the grand canonical ensemble. The number of particles, which is fixed in the canonical ensemble, is not necessarily the same as the average number of particles in the grand canonical ensemble.
巨正则系综和正则系综在热力学极限下是等价的，但当系统尺寸有限时，在这两个系综中得到的结果会相互偏离。在许多重要情况下，正则系综提供了合适的物理描述，但在相应的巨正则系综中进行计算通常要容易得多。我们提出一种基于巨正则系综中期望值的计算来计算正则系综中平均值的方法。在正则系综中固定的粒子数不一定与巨正则系综中的平均粒子数相同。
