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arXiv 1907.04037cond-mat.softphysics.chem-ph
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恒化学势下溶液晶体成核的模拟

Simulations of Crystal Nucleation from Solution at Constant Chemical Potential

Tarak Karmakar, Pablo M. Piaggi, Michele Parrinello

摘要:

一种广泛使用的晶体制备方法是将其从过饱和溶液中沉淀出来。在这样的过程中,溶液浓度的控制至关重要。成核过程,多晶型物的选择,和晶体的习惯取决于这个热力学参数至关重要。当在正则系综中进行模拟时,随着结晶相的沉积,溶液中的溶质被耗尽。热力学条件的这种不可避免的修改导致显著的伪像。在这里,我们采用Perego等人[J. Chem. Phys. 2015,142,144113]的恒定化学势分子动力学方法的思想来研究成核。我们的方法可以确定在恒定的过饱和度的晶核大小和成核速率。作为一个例子,我们研究了氯化钠从其过饱和水溶液中的均匀成核。

英文摘要:

A widely spread method of crystal preparation is to precipitate it from a supersaturated solution. In such a process, control of solution concentration is of paramount importance. Nucleation process, polymorph selection, and crystal habits depend crucially on this thermodynamic parameter. When performing simulations in the canonical ensemble as the crystalline phase is deposited the solution is depleted of solutes. This unavoidable modification of the thermodynamic conditions leads to significant artifact. Here we adopt the idea of the constant chemical potential molecular dynamics approach of Perego et al. [J. Chem. Phys. 2015, 142, 144113] to the study of nucleation. Our method allows determining the crystal nucleus size and nucleation rates at constant supersaturation. As an example we study the homogeneous nucleation of sodium chloride from its supersaturated aqueous solution.

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