Appraisal of dispersion damping functions for the effective fragment potential method

The effective fragment potential (EFP) is a polarizable force field whose physically-motivated functional form is parameterized in an automated way from <i>ab initio</i> calculations, and whose dispersion potential has been suggested as a correction for Hartree-Fock or density functional theory calculations. However, the parameter-free dispersion damping potentials that are currently used in EFP do not follow from a rigorous derivation and do not satisfy simple limits for the dispersion energy. We introduce several new damping expressions that correct these deficiencies, then evaluate their performance alongside existing damping functions using a new database of ionic liquid constituents. This data set, which we call IL195×8, consists of complete-basis coupled-cluster interaction energies for 195 ion pairs at each of 8 different intermolecular separations. Ultimately, we recommend a new parameter-free dispersion damping function as a replacement for the one that is currently used in EFP.

有效碎片势（effective fragment potential, EFP）是一类极化力场，其基于物理动机的泛函形式可通过从头算（ab initio）计算自动化拟合参数，且其色散势被提出可用于修正哈特里-福克或密度泛函理论计算。然而，当前EFP中使用的无参数色散阻尼势既未经过严格推导，也无法满足色散能的简单极限条件。我们提出了数种可修正这些缺陷的新型阻尼表达式，并借助一套全新的离子液体组分数据集，对其与现有阻尼函数的性能进行了评估。该数据集被命名为IL195×8，包含195个离子对在8种不同分子间间距下的完整基组耦合簇相互作用能。最终，我们推荐一款全新的无参数色散阻尼函数，以替代当前EFP中使用的阻尼势。