Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Chem Phys. 2012 Jan 21;136(3):034503. doi: 10.1063/1.3672810.
We develop a physically motivated many-body force field for CO(2), incorporating explicit three-body interactions parameterized on the basis of two- and three-body symmetry adapted perturbation theory (SAPT) calculations. The potential is parameterized consistently with, and builds upon, our successful SAPT-based two-body CO(2) model ("Schmidt, Yu, and McDaniel" (SYM) model) [K. Yu, J. G. McDaniel, and J. R. Schmidt, J. Phys Chem B 115, 10054 (2011)]. We demonstrate that three-body interactions are essential to achieve an accurate description of bulk properties, and that previous two-body models have therefore necessarily exploited large error cancellations to achieve satisfactory results. The resulting three-body model exhibits excellent second/third virial coefficients and bulk properties over the phase diagram, yielding a nearly empirical parameter-free model. We show that this explicit three-body model can be converted into a computationally efficient, density/temperature-dependent two-body model that reduces almost exactly to our prior SYM model in the high-density limit.
我们开发了一种基于物理的 CO(2)多体力场，其中包含基于二体和三体对称适应微扰理论 (SAPT) 计算参数化的显式三体相互作用。该势能与我们成功的基于 SAPT 的 CO(2)二体模型（“Schmidt、Yu 和 McDaniel”(SYM) 模型）一致，并在此基础上进行了扩展[K. Yu、J. G. McDaniel 和 J. R. Schmidt，J. Phys. Chem. B 115, 10054 (2011)]。我们证明了三体相互作用对于实现对体相性质的准确描述是必不可少的，因此以前的二体模型必然利用了大的误差抵消来获得令人满意的结果。由此产生的三体模型在相图上表现出优异的第二/第三维里系数和体相性质，得到了一个几乎经验无参数的模型。我们表明，这种显式三体模型可以转换为计算效率高、密度/温度依赖的二体模型，在高密度极限下几乎可以精确地简化为我们之前的 SYM 模型。
