CALCULATING ROVIBRATIONAL ENERGY LEVELS OF A TRIATOMIC MOLECULE WITH A SIMPLE LANCZOS METHOD
CALCULATING ROVIBRATIONAL ENERGY LEVELS OF A TRIATOMIC MOLECULE WITH A SIMPLE LANCZOS METHOD
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用简单的 LANCZOS 方法计算三原子分子的旋转振动能级
DOI：
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发表时间：
1999
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通讯作者：
T. Carrington
中科院分区：
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作者：
P. Sarkar;Nicolas M. Poulin;T. Carrington
本文提出了一种简单的Lanczos方法，由动能算符（KEO）计算三原子分子的振转能级，其中z轴垂直于分子平面。我们使用的旋转基函数是对称顶函数的线性组合，使所有的矩阵元素是真实的。对于某些分子，如果z轴选择垂直于分子平面，则旋转和振动之间的耦合不那么重要，但是z轴算子的奇异性比常用的y轴算子的奇异性更难处理。具有垂直于平面的z轴的KEO还减少了评估哈密顿矩阵矢量乘积所需的振动指数上的和的数量。使用一个新的自适应的基础和z轴的KEO，我们计算高J值的H2O的振转能级。即使在J=40时，我们也没有观察到四重团簇的形成。
We present a simple Lanczos method for calculating rovibrational energy levels of a triatomic molecule from a kinetic energy operator (KEO) with the z axis perpendicular to the molecular plane. We use rotational basis functions which are linear combinations of symmetric top functions so that all matrix elements are real. For some molecules, coupling between rotation and vibration is less important if the z axis is chosen perpendicular to the molecular plane, but the singularities of the z-axis operator are more difficult to deal with than those of the commonly used y-axis operator. The KEO with z axis perpendicular to the plane also reduces the number of sums over vibrational indices required to evaluate Hamiltonian matrix-vector products. Using a new symmetry-adapted basis and the z-axis KEO we calculate rovibrational energy levels of H2O for high J values. Even at J=40 we do not observe the formation of fourfold clusters.