Fawzy Wafaa M
Department of Chemistry, Murray State University, 1201 Jesse D Jones Hall, Murray, Kentucky 42071, USA.
J Chem Phys. 2009 Jul 28;131(4):044318. doi: 10.1063/1.3185726.
This work presents the first high level correlated ab initio study of the intermolecular potential energy surface of the ground electronic state of the O(2) (X (3)Sigma(g)(-))-H(2)(X) complex. This computational study was carried out using the CCSD(T) level of theory with the aug-cc-pVXZ basis sets, where X = D, T, Q, and 5. All calculated energies were corrected using the BSSE method. The lowest energy geometry and the shape of the intermolecular potential energy surface showed significant dependence on the size of the basis set as well as the BSSE corrections. The most accurate results were obtained using the CCSD(T)/aug-cc-pVQZ and CCSD(T)/aug-cc-pV5Z combinations with the BSSE corrections. These calculations yield a global minimum of C(2v) symmetry, where internuclear axes of the O(2) and H(2) moieties are parallel to each other. For this geometry, the D(e) value is 65.27(30) cm(-1), which is in excellent agreement with the CBS limit of 65.14 cm(-1). The distance between centers of masses of the H(2) and O(2) monomers within the complex is 3.225(1) A. Barrier heights to rotation of the H(2) and O(2) units by 180 degrees about the axis that connects their centers of masses are 24 and 159 cm(-1), respectively. The current results should stimulate microwave spectroscopic detection of the O(2)-H(2) complex.
这项工作首次对O₂(X³Σg⁻)-H₂(X)复合物基态的分子间势能面进行了高水平的相关从头算研究。该计算研究采用CCSD(T)理论水平和aug-cc-pVXZ基组进行，其中X = D、T、Q和5。所有计算能量均使用BSSE方法进行校正。最低能量几何结构和分子间势能面的形状显示出对基组大小以及BSSE校正有显著依赖性。使用带有BSSE校正的CCSD(T)/aug-cc-pVQZ和CCSD(T)/aug-cc-pV5Z组合获得了最精确的结果。这些计算得出一个具有C₂v对称性的全局最小值，其中O₂和H₂部分的核间轴相互平行。对于这种几何结构，D(e)值为65.27(30) cm⁻¹，与CBS极限65.14 cm⁻¹非常吻合。复合物中H₂和O₂单体质心之间的距离为3.225(1) Å。H₂和O₂单元绕连接它们质心的轴旋转180°的势垒高度分别为24和159 cm⁻¹。当前结果应会促进对O₂-H₂复合物的微波光谱检测。
