Pendular-limit representation of energy levels and spectra of symmetric- and asymmetric-top molecules
Pendular-limit representation of energy levels and spectra of symmetric- and asymmetric-top molecules
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DOI：
10.1103/physreva.70.013403
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发表时间：
2004-07
影响因子：
2.9
通讯作者：
R. Kanya;Y. Ohshima
中科院分区：
文献类型：
--
作者：
R. Kanya;Y. Ohshima
我们报告的理论研究有关的光谱的双稳态分子，这是受到大的静电相互作用的分子偶极和一个强大的外部场。经过适当的坐标变换和幂级数展开，得到了摆极限的零阶哈密顿量.非对称陀螺在强场中的运动可以用二维各向异性谐振子来描述，并引入了双态量子数来标记其能级。通过微扰处理，能量高达{lambda}{sup 0}阶解析表示的双态量子数。对称性的考虑也完成了使用适当的对称和不对称的顶部在均匀电场中的偶极刚体的群论。能级和波函数被分类到不可约的表示的群体和光学跃迁的选择规则进行了描述。在群论考虑的基础上，还讨论了无场和摆条件之间的能级相关性。对于对称和非对称的陀螺，通过展开跃迁偶极算符，导出了量子数的极限选择规则，并对每种跃迁类型的所有热激发组态的跃迁强度进行了解析计算.本制剂的效用已被验证的基础上的矩阵对角化与自由旋转基组的精确模型计算的比较。«少
We report theoretical investigations pertaining to spectroscopy of pendular-state molecules, which are subjected to the large electrostatic interaction between the molecular dipole and a strong external field. After an appropriate coordinate transformation and a power-series expansion with an order parameter {lambda} that represents the degree of pendular condition, the zeroth-order Hamiltonian for the pendular limit has been derived. Motions of asymmetric tops in a high field are well described as two-dimensional anisotropic harmonic oscillations, and pendular-state quantum numbers have been introduced to label the energy levels. By using perturbative treatments, energies up to the {lambda}{sup 0} order are represented analytically with the pendular-state quantum numbers. Symmetry considerations are also accomplished by using the group theory appropriate to dipolar rigid bodies of symmetric and asymmetric tops in a uniform electric field. Energy levels and wave functions are classified into irreducible representations of the groups and selection rules for optical transitions are described. Energy-level correlations between the field-free and pendular conditions are also discussed on the basis of the group theoretical considerations. For symmetric and asymmetric tops, pendular-limit selection rules on the quantum numbers are derived by expanding the transition-dipole operators on {lambda}, and transition strengths are analytically evaluated for all themore » excitation configurations with each of the transition types. Utilities of the present formulation have been verified by the comparison with exact model calculations based on the matrix diagonalization with a free-rotation basis set.« less