论文标题
Instanton速率恒定计算接近和高于交叉温度
Instanton Rate Constant Calculations Close to and Above the Crossover Temperature
论文作者
论文摘要
已知典型的Instanton理论高估了接近系统依赖性交叉温度的速率常数，并且不适用该温度。我们比较了使用最近的半古典速率表达式计算出的反应速率常数的准确性与规范Instanton理论的反应速率常数。我们表明，纯粹是从求解以自由度正交到intsanton路径的稳定性矩阵计算得出的速率常数不适用于任意低温，并采用两种方法来克服这一点。此外，作为开发方法的副产品，我们对规范插入理论进行了简单的校正，该理论可以减轻靠近交叉温度的速率常数的已知高估。合并的方法可以准确地沿整个温度范围重现规范理论的速率常数，而没有跨界温度附近的伪造高估。我们计算并比较了三种不同反应的费率常数：h中的h-棕色潜力，甲基羟基苯甲酰$ \ \ $ acetaldehyde和h $ _2 $ + oh $ \ oh $ \ to $ h + h + h + h $ _2 $ o。
Canonical instanton theory is known to overestimate the rate constant close to a system-dependent crossover temperature and is inapplicable above that temperature. We compare the accuracy of the reaction rate constants calculated using recent semi-classical rate expressions to those from canonical instanton theory. We show that rate constants calculated purely from solving the stability matrix for the action in degrees of freedom orthogonal to the instanton path is not applicable at arbitrarily low temperatures and employ two methods to overcome this. Furthermore, as a by-product of the developed methods, we derive a simple correction to canonical instanton theory that can alleviate this known overestimation of rate constants close to the crossover temperature. The combined methods accurately reproduce the rate constants of the canonical theory along the whole temperature range without the spurious overestimation near the crossover temperature. We calculate and compare rate constants on three different reactions: H in the Müller--Brown potential, methylhydroxycarbene $\to$ acetaldehyde and H$_2$ + OH $\to$ H + H$_2$O.
