State Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China.
Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Konkoly Thege út 29-33, 1121 Budapest, Hungary.
Molecules. 2019 May 10;24(9):1810. doi: 10.3390/molecules24091810.
The intermolecular interaction in difluoromethane, dichloromethane, dibromomethane, and diiodomethane dimers has been investigated using high level quantum chemical methods. The potential energy curve of intermolecular interaction along the C⋯C bond distance obtained using the coupled-cluster theory with singles, doubles, and perturbative triples excitations CCSD(T) were compared with values given by the same method, but applying the local (LCCSD(T)) and the explicitly correlated (CCSD(T)-F12) approximations. The accuracy of other theoretical methods-Hartree-Fock (HF), second order Møller-Plesset perturbation (MP2), and dispersion corrected DFT theory-were also presented. In the case of MP2 level, the canonical and the local-correlation cases combined with the density-fitting technique (DF-LMP2)theories were considered, while for the dispersion-corrected DFT, the empirically-corrected BLYP-D and the M06-2Xexchange-correlation functionals were applied. In all cases, the aug-cc-pVTZ basis set was used, and the results were corrected for the basis set superposition error (BSSE) using the counterpoise method. For each molecular system, several dimer geometries were found, and their mutual orientations were compared with the nearest neighbor orientations obtained in recent neutron scattering studies. The nature of the intermolecular interaction energy was discussed.
使用高精度量子化学方法研究了二氟甲烷、二氯甲烷、二溴甲烷和二碘甲烷二聚体的分子间相互作用。使用包含单、双和微扰三激发项的耦合簇理论（CCSD(T)）获得的分子间相互作用沿 C⋯C 键距离的势能曲线与相同方法给出的值进行了比较，但应用了局部（LCCSD(T））和显式相关（CCSD(T)-F12）近似。还介绍了其他理论方法——哈特ree-福克（HF）、二阶莫尔-普莱塞特微扰（MP2）和色散修正密度泛函理论的准确性。在 MP2 水平的情况下，考虑了正则和局部相关情况，并结合密度拟合技术（DF-LMP2）理论，而对于色散修正密度泛函理论，则应用了经验修正的 BLYP-D 和 M06-2X 交换相关泛函。在所有情况下，都使用了 aug-cc-pVTZ 基组，并使用平衡位能法（counterpoise method）对基组叠加误差（BSSE）进行了校正。对于每个分子体系，都找到了几个二聚体几何形状，并将它们的相互取向与最近的中子散射研究中获得的最近邻取向进行了比较。讨论了分子间相互作用能的性质。
