论文标题
分子中具有非对称同位素取代的隧道理论
Instanton theory of tunnelling in molecules with asymmetric isotopic substitutions
论文作者
论文摘要
我们考虑在非对称双孔系统中进行量子隧穿，这两个井中的局部最小值具有相同的能量，但频率略有不同。我们在这些不对称系统中得出了激体理论的概括，从而导致隧道矩阵元素的半经典表达，从而导致能级分裂。我们使用一组一维模型对方法进行基准测试，结果与数值精确的量子计算相比有利。使用环形聚合物激体款方法，我们应用了该方法来计算全尺寸的多种同位素基建造版本中的水平分割，并分析了零点能量差和隧道效应的相对贡献。
We consider quantum tunnelling in asymmetric double-well systems for which the local minima in the two wells have the same energy, but the frequencies differ slightly. We derive a generalization of instanton theory for these asymmetric systems, leading to a semiclassical expression for the tunnelling matrix element and hence the energy level splitting. We benchmark the method using a set of one- and two-dimensional models, for which the results compare favourably with numerically exact quantum calculations. Using the ring-polymer instanton approach, we apply the method to compute the level splittings in various isotopic-substituted versions of malonaldehyde in full dimensionality and analyse the relative contributions from the zero-point energy difference and tunnelling effects.
