Lehrstuhl für Thermodynamik und Energietechnik, Universität Paderborn, Warburger Str. 100, Paderborn 33098, Germany.
J Chem Phys. 2009 Nov 14;131(18):184104. doi: 10.1063/1.3259696.
Grand canonical molecular dynamics (GCMD) is applied to the nucleation process in a metastable phase near the spinodal, where nucleation occurs almost instantaneously and is limited to a very short time interval. With a variant of Maxwell's demon, proposed by McDonald [Am. J. Phys. 31, 31 (1963)], all nuclei exceeding a specified size are removed. In such a steady-state simulation, the nucleation process is sampled over an arbitrary time span and all properties of the metastable state, including the nucleation rate, can be obtained with an increased precision. As an example, a series of GCMD simulations with McDonald's demon is carried out for homogeneous vapor to liquid nucleation of the truncated-shifted Lennard-Jones (tsLJ) fluid, covering the entire relevant temperature range. The results are in agreement with direct nonequilibrium MD simulation in the canonical ensemble. It is confirmed for supersaturated vapors of the tsLJ fluid that the classical nucleation theory underpredicts the nucleation rate by two orders of magnitude.
巨正则分子动力学（GCMD）被应用于亚稳相中旋节线附近的成核过程，在该过程中成核几乎是瞬间发生的，并限于非常短的时间间隔。通过 McDonald [Am. J. Phys. 31, 31 (1963)] 提出的麦克斯韦妖的变体，所有超过指定尺寸的核都被移除。在这种稳态模拟中，成核过程在任意时间跨度内进行采样，并且可以以更高的精度获得亚稳态的所有性质，包括成核速率。作为一个例子，对截断移动 Lennard-Jones（tsLJ）流体的均相蒸汽到液体成核进行了一系列带有 McDonald 妖的 GCMD 模拟，涵盖了整个相关的温度范围。结果与正则系综中的直接非平衡 MD 模拟一致。对于 tsLJ 流体的过饱和蒸汽，经典成核理论预测的成核速率低了两个数量级。
