Yu Xin, Leitner David M
Department of Chemistry, University of Nevada, Reno, 89557, USA.
J Chem Phys. 2005 Sep 8;123(10):104503. doi: 10.1063/1.2009732.
We compute thermal transport coefficients for liquid and glassy water in terms of the vibrations of the quenched liquid. The thermal conductivity and thermal diffusivity are computed for H(2)O and D(2)O at densities from 0.93 to 1.2 g cm(-3). The computed thermal diffusivity of liquid water is in reasonable agreement with measured values and is found to increase with increasing temperature due largely to the thermal accessibility of delocalized librational modes. The influence of structure and density on the thermal conductivity of amorphous ices is investigated. The calculations reveal that density alone is unable to explain the measured thermal conductivity of amorphous ices, particularly low-density amorphous ices, for which the thermal conductivity decreases with increasing temperature near 100 K. To investigate the influence of structure on thermal transport in amorphous ices we have computed the thermal transport coefficients for low-density amorphous ices prepared in two different ways, one formed by quenching the liquid at 0.93 g cm(-3) and the other by distortion of cubic ice at the same density. The computed thermal conductivity of the latter is higher, but the structures of both forms are too disordered for the thermal conductivity to exhibit the unusual variation observed experimentally.
我们根据猝灭液体的振动来计算液态水和玻璃态水的热传输系数。计算了密度在0.93至1.2 g cm⁻³范围内的H₂O和D₂O的热导率和热扩散率。计算得到的液态水的热扩散率与测量值合理吻合，并且发现其随温度升高而增加，这主要归因于离域振动模式的热可及性。研究了结构和密度对非晶冰热导率的影响。计算结果表明，仅密度无法解释测量得到的非晶冰的热导率，特别是低密度非晶冰，其在100 K附近热导率随温度升高而降低。为了研究结构对非晶冰热传输的影响，我们计算了通过两种不同方式制备的低密度非晶冰的热传输系数，一种是在0.93 g cm⁻³下猝灭液体形成的，另一种是在相同密度下通过立方冰的畸变形成的。后者计算得到的热导率更高，但两种形式的结构都过于无序，以至于热导率无法呈现出实验观察到的异常变化。
