Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
J Phys Chem A. 2009 Dec 31;113(52):14952-60. doi: 10.1021/jp905045b.
The quantum mechanical theory for the scattering of two identical rigid rotors is reviewed and applied to the collision of O2(3Sigma(g)-) molecules using a new accurate ab initio potential energy surface (PES) for the quintet state of the composite system. The PES is based on calculations using restricted coupled-cluster theory with singles, doubles, and perturbative triple excitations [RCCSD(T)] [Bartolomei; et al. J. Chem. Phys. 2008, 128, 214304.]. This PES is extended here for large intermolecular distances using the ab initio long-range coefficients of Hettema et al. [J. Chem. Phys. 1994, 100, 1297.]. Elastic and rotationally inelastic integral cross sections have been obtained by means of close coupling calculations in the subthermal energy range (center-of-mass velocities below 500 m/s). Results are compared with those obtained using a PES derived from molecular beam experiments [Aquilanti; et al. J. Am. Chem. Soc. 1999, 121, 10794.]. General agreement is found between both PESs, although the experimentally derived PES appears as somewhat more anisotropic at least for the studied energy range. There is, however, a significant difference in the absolute value of the elastic cross sections that is due to differences in the long-range dispersion interaction. The performance of the ab initio PES for higher velocities (relevant to experiments) is also explored by retaining just the isotropic component of the interaction. A satisfactory agreement is found for the shape of the glory pattern but shifted toward lower absolute values of the cross sections.
回顾了两个相同刚性转子散射的量子力学理论，并将其应用于 O2(3Σ(g)-)分子的碰撞，使用新的准确从头算势能面（PES）研究了复合体系的五重态。该PES 基于使用受限耦合簇理论（RCCSD(T)）[Bartolomei；等。J. Chem. Phys. 2008, 128, 214304.]进行计算的计算。在这里，通过使用 Hettema 等人的从头算长程系数[J. Chem. Phys. 1994, 100, 1297.]对该 PES 进行了扩展，以适用于较大的分子间距离。通过在亚热能量范围内（质心速度低于 500 m/s）的紧密耦合计算获得了弹性和旋转非弹性积分截面。结果与使用从分子束实验得出的 PES 进行的比较[ Aquilanti；等。J. Am. Chem. Soc. 1999, 121, 10794.]。发现两个 PES 之间存在普遍的一致性，尽管从实验得出的 PES 至少在研究的能量范围内看起来有些各向异性。然而，在弹性截面的绝对值上存在显著差异，这是由于长程色散相互作用的差异造成的。通过保留相互作用的各向同性分量，还探索了从头算 PES 在更高速度（与实验相关）下的性能。对于截面的绝对值较低的情况，发现截面的形状与荣耀模式相符。
