One of the most striking phenomena in condensed matter physics is the occurrence of abrupt transitions in the structure of a substance at certain temperatures or pressures. These are first-order phase transitions, and examples such as the freezing of water and the condensation of vapors to form mist in the atmosphere are familiar in everyday life. A fascinating aspect of these phenomena is that the conditions at which the transformation takes place can sometimes vary. The freezing point of water is not always 0 C: the liquid can be supercooled considerably if it is pure enough and treated carefully. Similarly, it is possible to raise the pressure of a vapor above the so-called saturation vapor pressure, at which condensation ought to take place according to the thermodynamic properties of the separate phases. Both these phenomena occur because of the requirement for nucleation. In practice, the transformation takes place through the creation of small aggregates, or clusters, of the daughter phase out of the parent phase. In spite of the familiarity of the phenomena involved, accurate calculation of the rate of cluster formation for given conditions of the parent phase meets serious difficulties. This is because the properties of the small clusters are insufficiently well known.

中文翻译：

---

前言

凝聚态物理学中最引人注目的现象之一是，在一定温度或压力下，物质结构突然发生转变。这些是一阶的相变，在日常生活中，例如水的冻结和水蒸气的凝结以在大气中形成雾的例子是熟悉的。这些现象的一个令人着迷的方面是，发生转化的条件有时可能会发生变化。水的凝固点并不总是0 C：如果液体足够纯净并经过仔细处理，则可以将其过冷。类似地，可以将蒸汽的压力升高到所谓的饱和蒸汽压力之上，根据分离的相的热力学性质，应当在该饱和蒸汽压力下发生冷凝。这两种现象都是由于需要成核而发生的。在实践中，转换是通过创建子阶段到父阶段之外的小聚合或集群来进行的。尽管对所涉及的现象很熟悉，但对于给定的母相条件，准确计算团簇形成的速率仍存在严重的困难。这是因为小簇的性质是众所周知的。