Martelli Fausto, Torquato Salvatore, Giovambattista Nicolas, Car Roberto
Department of Chemistry, Princeton University, Princeton, New Jersey, USA.
Department of Physics, Princeton University, Princeton, New Jersey, USA.
Phys Rev Lett. 2017 Sep 29;119(13):136002. doi: 10.1103/PhysRevLett.119.136002.
We investigate the large-scale structure of amorphous ices and transitions between their different forms by quantifying their large-scale density fluctuations. Specifically, we simulate the isothermal compression of low-density amorphous ice (LDA) and hexagonal ice to produce high-density amorphous ice (HDA). Both HDA and LDA are nearly hyperuniform; i.e., they are characterized by an anomalous suppression of large-scale density fluctuations. By contrast, in correspondence with the nonequilibrium phase transitions to HDA, the presence of structural heterogeneities strongly suppresses the hyperuniformity and the system becomes hyposurficial (devoid of "surface-area fluctuations"). Our investigation challenges the largely accepted "frozen-liquid" picture, which views glasses as structurally arrested liquids. Beyond implications for water, our findings enrich our understanding of pressure-induced structural transformations in glasses.
我们通过量化非晶态冰的大规模密度涨落来研究其大规模结构以及不同形式之间的转变。具体而言，我们模拟了低密度非晶态冰（LDA）和六方冰的等温压缩过程，以生成高密度非晶态冰（HDA）。HDA和LDA都近乎超均匀；也就是说，它们的特征是大规模密度涨落受到异常抑制。相比之下，与向HDA的非平衡相变相对应，结构不均匀性的存在强烈抑制了超均匀性，并且系统变得低表面（缺乏“表面积涨落”）。我们的研究挑战了被广泛接受的“冻结液体”图景，该图景将玻璃视为结构上停滞的液体。除了对水的影响之外，我们的发现丰富了我们对玻璃中压力诱导的结构转变的理解。
