Hernandez-Lamoneda Ramón, Rosas Victor Hugo Uc, Uruchurtu Margarita I Bernal, Halberstadt Nadine, Janda Kenneth C
Centro de Investigaciones Químicas, UAEM, Cuernavaca, Mor. 62210, México.
J Phys Chem A. 2008 Jan 10;112(1):89-96. doi: 10.1021/jp077074i. Epub 2007 Dec 13.
All electron ab initio calculations for the interaction of H2O with Cl2 and Br2 are reported for the ground state and the lowest triplet and singlet Pi excited states as a function of both the X-X and O-X bond lengths (X = Cl or Br). For the ground state and lowest triplet state, the calculations are performed with the coupled cluster singles, doubles, and perturbative triple excitation level of correlation using an augmented triple-zeta basis set. For the 1Pi state the multireference average quadratic coupled cluster technique was employed. For several points on the potential, the calculations were repeated with the augmented quadruple-zeta basis set. The ground-state well depths were found to be 917 and 1,183 cm-1 for Cl2 and Br2, respectively, with the triple-zeta basis set, and they increased to 982 and 1,273 cm-1 for the quadruple-zeta basis set. At the geometry of the ground-state minimum, the lowest energy state corresponding to the unperturbed 1Pi states of the halogens increases in energy by 637 and 733 cm-1, respectively, relative to the ground-state dissociation limit of the H2O-X2 complex. Adding the attractive ground-state interaction energy to that of the repulsive excited state predicts a blue-shift, relative to that of the free halogen molecules, of approximately 1,600 cm-1 for H2O-Cl2 and approximately 2,000 cm-1 for H2O-Br2. These vertical blue-shifts for the dimers are greater than the shift of the band maximum upon solvation of either halogen in liquid water.
报道了关于H₂O与Cl₂和Br₂相互作用的所有电子从头算计算，计算针对基态、最低三重态和单重态π激发态，是X - X键长和O - X键长（X = Cl或Br）的函数。对于基态和最低三重态，使用增强三重ζ基组在耦合簇单双激发和微扰三重激发相关水平上进行计算。对于¹π态，采用多参考平均二次耦合簇技术。对于势能上的几个点，使用增强四重ζ基组重复计算。使用三重ζ基组时，发现Cl₂和Br₂的基态阱深分别为917和1183 cm⁻¹，使用四重ζ基组时，阱深增加到982和1273 cm⁻¹。在基态最小值的几何构型下，相对于H₂O - X₂复合物的基态解离极限，对应于卤素未受扰动的¹π态的最低能量态能量分别增加637和733 cm⁻¹。将吸引性的基态相互作用能与排斥性的激发态相互作用能相加预测，相对于自由卤素分子，H₂O - Cl₂的蓝移约为1600 cm⁻¹，H₂O - Br₂的蓝移约为2000 cm⁻¹。这些二聚体的垂直蓝移大于任何一种卤素在液态水中溶剂化时能带最大值的移动。
