Dual-Level Approach to Instanton Theory,Journal of Chemical Theory and Computation

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Dual-Level Approach to Instanton Theory
Journal of Chemical Theory and Computation ( IF 5.7 ) Pub Date : 2018-03-12 00:00:00 , DOI: 10.1021/acs.jctc.8b00068
Jan Meisner ₁ , Johannes Kästner ₁

Affiliation

Instanton theory is an established method to calculate rate constants of chemical reactions including atom tunneling. Technical and methodological improvements increased its applicability. Still, a large number of energy and gradient calculations is necessary to optimize the instanton tunneling path, and second derivatives of the potential energy along the tunneling path have to be evaluated, restricting the range of suitable electronic structure methods. To enhance the applicability of instanton theory, we present a dual-level approach in which instanton optimizations and Hessian calculations are performed using an efficient but approximate electronic structure method, and the potential energy along the tunneling path is recalculated using a more accurate method. This procedure extends the applicability of instanton theory to high-level electronic structure methods for which analytic gradients may not be available, like local linear-scaling approaches. We demonstrate for the analytical Eckart barrier and three molecular systems how the dual-level instanton approach corrects for the largest part of the error caused by the inaccuracy of the efficient electronic structure method. This reduces the error of the calculated rate constants significantly.

中文翻译：

瞬态理论的双层方法

Instanton理论是一种计算包括原子隧穿在内的化学反应速率常数的既定方法。技术和方法上的改进提高了其适用性。仍然需要大量的能量和梯度计算来优化瞬时隧穿路径，并且必须评估沿隧穿路径的势能的二阶导数，从而限制了合适的电子结构方法的范围。为了增强实例化理论的适用性，我们提出了一种双层方法，其中使用有效但近似的电子结构方法执行实例化优化和Hessian计算，并使用更精确的方法重新计算沿隧穿路径的势能。此过程将实例化理论的适用性扩展到可能无法使用解析梯度的高级电子结构方法，例如局部线性缩放方法。我们为解析的Eckart势垒和三个分子系统论证了双级瞬时子方法如何纠正由有效电子结构方法的不准确所引起的最大误差。这显着减小了所计算的速率常数的误差。

更新日期：2018-03-12

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