Makarewicz Jan
Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL 60-780 Poznań, Poland.
J Chem Phys. 2006 Jan 28;124(4):044310. doi: 10.1063/1.2162162.
The van der Waals vibrational states and the structure of the vibronic spectrum of s-tetrazine-argon complex have been studied by the ab initio methods. The potential-energy surface of the ground S(0) electronic state of the complex has been constructed by fitting the analytical many-body expansion to a large set of the interaction energy values computed using the second-order Møller-Plesset perturbation theory combined with the standard aug-cc-pVDZ basis set. The equilibrium structure of the complex found is that with argon located above the tetrazine ring at a distance of 3.394 A. The calculated dissociation energy of 354 cm(-1) is compatible with the experiment. The van der Waals energy spectrum calculated from the potential-energy surface is explained analyzing a correlation with a simpler energy spectrum of benzene-argon. A new assignment of the S(0)-S(1) vibronic spectrum is proposed on the basis of the rigorous selection rules, vibrational energy levels in S(0) and S(1) states and vibronic transition intensities calculated from the electronic transition dipole moment surfaces.
采用从头算方法研究了s-四嗪-氩络合物的范德华振动态和振转光谱结构。通过将解析多体展开式拟合到使用二阶Møller-Plesset微扰理论结合标准aug-cc-pVDZ基组计算得到的大量相互作用能值，构建了该络合物基态S(0)电子态的势能面。所发现的络合物平衡结构是氩位于四嗪环上方，距离为3.394 Å。计算得到的354 cm⁻¹的离解能与实验结果相符。通过分析与苯-氩更简单的能谱的相关性，解释了从势能面计算得到的范德华能谱。基于严格的选择规则、S(0)和S(1)态的振动能级以及从电子跃迁偶极矩面计算得到的振转跃迁强度，提出了S(0)-S(1)振转光谱的新归属。
