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首页> 外文期刊>Physica, B. Condensed Matter >Hindered rotation of OD-Li in MgO: IR absorption experiments and theory
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Hindered rotation of OD-Li in MgO: IR absorption experiments and theory

机译：OD-Li在MgO中的旋转受阻：红外吸收实验和理论

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摘要

We have measured the infrared absorption of the broad stretch bands of the OD-Li and OH-Li complexes in MgO at various temperatures. At low temperature (similar to 3.5-66 K) we find that the band for OD-Li is composed of several distinct components with definite temperature dependences, indicating a manifold of closely spaced levels associated with both the ground and excited vibrational levels. We use a variety of theoretical approaches to show that the data are consistent with the OD or OH performing hindered rotational motion through a channel around the z-axis, and that the substitutional Li is involved in the rotational motion. Density functional theory calculations using CRYSTAL2003 show that the static equilibrium of the H or D bonded to an 0 is displaced from the O-Li axis in a (1, 1, 0) direction, while the Li is displaced in a (-1, -1, 0) direction as a result of Coulombic repulsion. Thus, there are four equivalent minima in the channel around the z-axis, imposing C-4v symmetry. We develop a parameterized four-basis model consistent with this symmetry that predicts an energy level diagram and transition intensities consistent with experiment. To determine whether the Li is involved in the motion, we also model the system with both two- and three-dimensional rotations. We find that the rotational constant required to fit experiment must be smaller by at least a factor of 2 relative to its value if only the OH or OD were involved in the motion, supporting the idea that the Li must be involved as well. (c) 2007 Elsevier B.V.. All rights reserved.
机译：我们已经测量了在各种温度下MgO中OD-Li和OH-Li配合物的宽拉伸带的红外吸收。在低温（类似于3.5-66 K）下，我们发现OD-Li的谱带由几个具有明确的温度依赖性的不同成分组成，表明与地面和激发振动能级相关的紧密间隔的能级流形。我们使用各种理论方法来证明数据与OD或OH通过绕z轴的通道执行受阻碍的旋转运动一致，并且替代Li参与了旋转运动。使用CRYSTAL2003进行的密度泛函理论计算表明，键合到0的H或D的静态平衡从O-Li轴沿（1，1，0）方向位移，而Li沿（-1，1， -1，0）是库仑排斥的结果。因此，在围绕z轴的通道中存在四个等效的最小值，这导致C-4v对称。我们开发了与此对称性相一致的参数化四基模型，该模型可预测能级图和与实验相符的跃迁强度。为了确定Li是否参与运动，我们还对系统进行了二维和三维旋转建模。我们发现，如果只有OH或OD参与运动，则适合实验所需的旋转常数必须比其值小至少2倍，这也支持Li也必须参与的观点。 （c）2007 Elsevier B.V.。保留所有权利。

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