The adiabatic approximation I. The physical background of the Born-Handy ansatz
The adiabatic approximation I. The physical background of the Born-Handy ansatz
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绝热近似 I. Born-Handy ansatz 的物理背景
DOI：
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发表时间：
1997
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通讯作者：
W. Kutzelnigg
中科院分区：
文献类型：
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作者：
W. Kutzelnigg
目前有两种方法来计算势能超曲面的绝热修正：首先是一种严谨的方法，从分离质心运动开始，在分子固定的框架中得到相当复杂的相对坐标表达式；其次是一种实用的方法，最近由Handy等人提倡，从实验室系统中的一项Born ansatz开始，得到一个相当简单的核坐标表达式。在这个笔记中表明，后者的简单表达式也可以严格地得到，即通过首先分离质心运动。分析了为什么实用的方法会导致正确的结果，以及为什么对绝热修正的评估不需要指定分子固定框架。
There are two current ways to evaluate the adiabatic corrections to a potential energy hypersurface: firstly a rigorous way in which one starts with the separation of the centre-of-mass motion and where one gets rather complicated expressions in terms of relative coordinates in a molecule-fixed frame, and secondly a pragmatic way, recently advocated by Handy et al., where one starts from a one-term Born ansatz in the laboratory system and arrives at a rather simple expression in terms of nuclear coordinates. In this note it is shown that the latter simple expression can also be obtained rigorously, that is by separating the centre-of-mass motion first. Why the pragmatic approach leads to a correct result, and why the specification of a molecule-fixed frame is not necessary for the evaluation of the adiabatic corrections, are analysed.