Density of States Partitioning Method for Calculating the Free Energy of Solids
Density of States Partitioning Method for Calculating the Free Energy of Solids
复制标题
DOI：
10.1021/ct3007056
复制
发表时间：
2013-01-01
影响因子：
5.5
通讯作者：
Wheatley, Richard J.
中科院分区：
文献类型：
--
作者：
Do, Hainam;Wheatley, Richard J.
本文提出了一种结合笼模型和状态密度划分技术计算任意固体自由能的新方法。多余的自由能分为两部分，非相互作用和相互作用。非相互作用固体的多余自由能是通过划分其相对于理想气体的几何构型空间来计算的。这个量取决于晶格类型和分子的数量。相互作用固体相对于非相互作用固体的多余自由能，使用状态密度划分和笼模型计算。笼型模型比单元型模型具有更小的构型空间，更能代表固体构型的平衡分布。由于配分函数（也就是自由能）是由与温度无关的态密度得到的，所以任何条件下的平衡热力学性质都可以通过改变密度得到。我们用干冰的自由能来说明我们的方法。
We propose a new simulation method, which combines a cage model and a density of states partitioning technique, to compute the free energy of an arbitrary solid. The excess free energy is separated into two contributions, noninteracting and interacting. The excess free energy of the noninteracting solid is computed by partitioning its geometrical configuration space with respect to the ideal gas. This quantity depends on the lattice type and the number of molecules. The excess free energy of the interacting solid, with respect to the noninteracting solid, is calculated using density of states partitioning and a cage model. The cage model is better than the cell model in that it has a smaller configuration space and better represents the equilibrium distribution of solid configurations. Since the partition function (and hence free energy) is obtained from the density of states, which is independent of the temperature, equilibrium thermodynamic properties at any condition can be obtained by varying the density. We illustrate our method in the context of the free energy of dry ice.