水二聚体分子间相互作用势

利用超分子二阶到四阶多体微扰理论和扩展的相关一致基组(aug-cc-pVTZ)结合有效的中点键函数(3s3p2d1f1g)计算水二聚物的平衡结构和分子间相互作用势,并用平衡方法修正基组重叠误差.在MP2/aug-cc-pVTZ理论级别优化水二聚物几何构型.与正常优化的结果相比,平衡修正优化得到的RO-O和α值分别轻微的增加0.002 nm和0.19°,同时,θ值减小0.013°.在MP2水平利用扩展的相关一致基组结合有效键函数,预言了RO-O和ΔECP值分别为0.0923 nm和-4.86 kcal/mol,计算结果与实验值符合得很好.用exp-4.2势函数拟合分子间相互作用能的离散点,拟合结果与从头算计算的结果一致.

Intermolecular interaction potentials of water dimer

The equilibrium structure and intermolecular interaction potentials of water dimer have been calculated using supermolecular many-body perturbation theory at the second-order to fourth-order levels. The augmented correlation-consistent basis set aug-cc-pVTZ and the effective midbond functions {3s3p2d1f1g} are employed. Basis set superposition error is corrected by applying the counterpoise procedure. At the MP2 level with aug-cc-pVTZ basis set, the values of RO-O and α slightly increase 0.002 nm and 0.19°, respectively, while the magnitude of θ drops 0.013° on the CP-optimization geometry compared with the normal optimization geometry. The MP2 calculations with augmented correlation-consistent basis set combining with effective midbond functions predict the values of Ro-o, and ΔECP, for 0.293 nm and -4.86 kcal/mol respectively, which are in better agreement with experiment. The discrete grid of calculated intermolecular interaction energies is fitted to exp-4.2 potential function. The agreement between the fitting and the ab initio results is excellent.