Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.
J Phys Chem A. 2013 Aug 15;117(32):7542-52. doi: 10.1021/jp4018579. Epub 2013 May 28.
The three-body nonadditive interaction energy between argon atoms was calculated at 300 geometries using coupled cluster methods up to single, double, triple, and noniterative quadruple excitations [CCSDT(Q)], and including the core correlation and relativistic effects. The uncertainty of the calculated energy was estimated at each geometry. The analytic function fitted to the energies is currently the most accurate three-body argon potential. Values of the third virial coefficient C(T) with full account of quantum effects were computed from 80 to 10000 K by a path-integral Monte Carlo method. The calculation made use of an existing high-quality pair potential [Patkowski, K.; Szalewicz, K. J. Chem. Phys. 2010, 133, 094304] and of the three-body potential derived in the present work. Uncertainties in the potential were propagated to estimate uncertainties in C(T). The results were compared with available experimental data, including some values of C(T) newly derived in this work from previously published high-accuracy density measurements. Our results are generally consistent with the available experimental data in the limited range of temperatures where data exist, but at many conditions, especially at higher temperatures, the uncertainties of our calculated values are smaller than the uncertainties of the experimental values.
采用耦合簇方法在 300 种几何构型上计算了氩原子的三体非加和相互作用能，计算方法包括单、双、三激发和非迭代四激发[CCSDT(Q)]，并考虑了核心相关和相对论效应。在每个几何构型上都估算了计算能量的不确定度。拟合能量的解析函数是目前最精确的三体氩势。利用路径积分蒙特卡罗方法，在量子效应完全考虑的情况下，从 80 到 10000 K 计算了第三维里系数 C(T)。计算利用了现有的高质量双体势[Patkowski, K.; Szalewicz, K. J. Chem. Phys. 2010, 133, 094304]和本工作中推导出的三体势。将势中的不确定度传播以估计 C(T)的不确定度。将结果与现有的实验数据进行了比较，包括本工作中从先前发表的高精度密度测量中推导出的一些 C(T)值。我们的结果与有限温度范围内现有的实验数据基本一致，但是在许多条件下，尤其是在较高温度下，我们计算值的不确定度比实验值的不确定度小。
