Interdisciplinary Laboratory for Computational Science, FBK-CMM and University of Trento, via Sommarive 18, I-38123 Povo (TN), Italy.
J Chem Phys. 2012 Oct 21;137(15):154308. doi: 10.1063/1.4757565.
We employ path-integral Monte Carlo techniques to compute the second virial coefficient as a function of temperature for molecular hydrogen (H(2)), deuterium (D(2)), and tritium (T(2)), along with the mixed isotopologues HD, HT, and DT. The calculations utilize a new six-dimensional (6D) potential, which is derived by combining our previous high-quality ground-state 4D potential for the H(2) dimer with the 6D potential of Hinde. This new 6D potential is reduced to a set of 4D potentials by fixing the intramolecular coordinates at their expectation values for each temperature and isotopic combination. The results for H(2) are in good agreement with experimental data; the effect of the temperature dependence of the average bond length is only significant above approximately 1000 K. For D(2) and HD, the available experimental data are much more limited; our results agree with the data and provide reliable values at temperatures where no experimental data exist. For the species containing tritium, our results provide the only data available.
我们采用路径积分蒙特卡罗技术，计算了分子氢（H2）、氘（D2）和氚（T2）以及混合同位素 HD、HT 和 DT 的第二维里系数随温度的函数关系。该计算采用了一种新的六维（6D）势能，它是通过将我们之前的高质量 H2 二聚体的 4D 基态势能与 Hinde 的 6D 势能相结合而得到的。对于每个温度和同位素组合，通过将分子内坐标固定在其期望值，这个新的 6D 势能可以简化为一组 4D 势能。对于 H2，结果与实验数据吻合良好；平均键长的温度依赖性的影响仅在约 1000 K 以上才显著。对于 D2 和 HD，可用的实验数据要少得多；我们的结果与数据一致，并在没有实验数据的温度下提供可靠的值。对于含有氚的物质，我们的结果提供了唯一可用的数据。
