Altunata Serhan N, Coy Stephen L, Field Robert W
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
J Chem Phys. 2006 May 21;124(19):194302. doi: 10.1063/1.2192518.
Results of ab initio R-matrix calculations [S. N. Altunata et al., J. Chem. Phys. 123, 084319 (2005)] indicate the presence of a broad shape resonance in electron-CaF(+) scattering for the (2)Sigma(+) electronic symmetry near the ionization threshold. The properties of this shape resonance are analyzed using the adiabatic partial-wave expansion of the scattered electron wave function introduced by Le Dourneuf et al. [J. Phys. B 15, L685 (1982)]. The qualitative aspects of the shape resonance are explained by an adiabatic approximation on the electronic motion. Mulliken's rule for the structure of the Rydberg state wave functions [R. S. Mulliken, J. Am. Chem. Soc. 86, 3183 (1964)] specifies that, except for an (n*)(-32) amplitude scale factor, every excited state wave function within one Rydberg series is built on an innermost lobe that remains invariant in shape and nodal position as a function of the excitation energy. Mulliken's rule implies a weak energy dependence of the quantum defects for an unperturbed molecular Rydberg series, which is given by the Rydberg-Ritz formula. This zero-order picture is violated by a single (2)Sigma(+) CaF Rydberg series at all Rydberg state energies (n*=5-->infinity, more so with increasing n*) below the ionization threshold, under the broad width of the shape resonance. Such a violation is diagnostic of a global "scarring" of the Rydberg spectrum, which is distinct from the more familiar local level perturbations.
从头算R矩阵计算结果[S. N. 阿尔图纳塔等人，《化学物理杂志》123, 084319 (2005)]表明，在电离阈值附近，对于(2)Σ⁺电子对称性，电子-CaF⁺散射中存在一个宽的形状共振。使用勒杜尔纳夫等人引入的散射电子波函数的绝热分波展开来分析这个形状共振的性质[《物理B杂志》15, L685 (1982)]。通过对电子运动的绝热近似来解释形状共振的定性方面。穆利肯关于里德堡态波函数结构的规则[R. S. 穆利肯，《美国化学会志》86, 3183 (1964)]规定，除了一个(n*)⁻³²振幅比例因子外，一个里德堡系列内的每个激发态波函数都基于一个最内层的叶瓣构建，其形状和节点位置作为激发能量的函数保持不变。穆利肯规则意味着对于未受扰动的分子里德堡系列，量子亏损对能量的依赖性较弱，这由里德堡-里兹公式给出。在形状共振的宽宽度下，在电离阈值以下的所有里德堡态能量(n* = 5→∞，随着n*增加更明显)，一个单一的(2)Σ⁺ CaF里德堡系列违反了这个零阶图像。这种违反是里德堡光谱全局“疤痕化”的诊断依据，这与更熟悉的局部能级微扰不同。
