Thermodynamic, Diffusional, and Structural Anomalies in Rigid-Body Water Models
Thermodynamic, Diffusional, and Structural Anomalies in Rigid-Body Water Models
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DOI：
10.1021/jp110695t
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发表时间：
2011-06-02
影响因子：
3.3
通讯作者：
Chakravarty, Charusita
中科院分区：
文献类型：
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作者：
Agarwal, Manish;Alam, Mohammad Parvez;Chakravarty, Charusita
TIP 4P/2005水模型的结构、密度、熵和扩散率异常在很宽的密度和温度范围内绘制出来。在250 ~ 275 K温度范围内，该模型的最大密度温度（TMD）轨迹与实验TMD轨迹非常接近。四个不同的水模式（mTIP 3 P，TIP 4P，TIP 5 P和SPC/E）与TIP 4P/2005模式的异常行为进行了比较。对于所有的水模型，异常行为的密度区域由大约0.85-0.90 g cm（-3）的低密度极限和大约1.10-1.15 g cm（-3）的高密度极限限定。在各种模型的密度异常的起始温度显示出更大的变化，从202 K的mTIP 3 P到289 K的TIP 5 P。各种水模型的顺序映射在质量上非常相似，在q（泰特）-tau平面上几乎可以重叠的结构异常区域。水模型的相图与液态异常区域的比较表明，结晶相对水模型的选择比液态异常敏感得多;例如，SPC/E和TIP 4P/2005显示了定性相似的液态异常，但相图非常不同。在所有的模型中，液体中的异常发生在比熔化线从负斜率变为正斜率的压力低得多的压力下。在这项研究中的结果表明，水模型的结构熵扩散率的关系，可以与实验进行比较，并用于开发更好的原子和粗粒度的水模型的几个方面。
Structural, density, entropy, and diffusivity anomalies of the TIP4P/2005 model of water are mapped out over a wide range of densities and temperatures. The locus of temperatures of maximum density (TMD) for this model is very close to the experimental TMD locus for temperatures between 250 and 275 K. Four different water models (mTIP3P, TIP4P, TIP5P, and SPC/E) are compared with the TIP4P/2005 model in terms of their anomalous behavior. For all the water models, the density regimes for anomalous behavior are bounded by a low-density limit at around 0.85-0.90 g cm(-3) and a high-density limit at about 1.10-1.15 g cm(-3). The onset temperatures of the density anomaly in the various models show a much greater variation, ranging from 202 K for mTIP3P to 289 K for TIP5P. The order maps for the various water models are qualitatively very similar with the structurally anomalous regions almost superimposable in the q(tet)-tau plane. Comparison of the phase diagrams of water models with the region of liquid-state anomalies shows that the crystalline phases are much more sensitive to the choice of water models than the liquid state anomalies; for example, SPC/E and TIP4P/2005 show qualitatively similar liquid state anomalies but very different phase diagrams. The anomalies in the liquid in all the models occur at much lower pressures than those at which the melting line changes from negative to positive slope. The results in this study demonstrate several aspects of structure-entropy-diffusivity relationships of water models that can be compared with experiment and used to develop better atomistic and coarse-grained models for water.