Litman Yair, Rossi Mariana
Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany and Institute for Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany.
Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany and MPI for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany.
Phys Rev Lett. 2020 Nov 20;125(21):216001. doi: 10.1103/PhysRevLett.125.216001.
The nuclear tunneling crossover temperature (T_{c}) of hydrogen transfer reactions in supported molecular-switch architectures can lie close to room temperature. This calls for the inclusion of nuclear quantum effects (NQEs) in the calculation of reaction rates even at high temperatures. However, computations of NQEs relying on standard parametrized dimensionality-reduced models quickly become inadequate in these environments. In this Letter, we study the paradigmatic molecular switch based on porphycene molecules adsorbed on metallic surfaces with full-dimensional calculations that combine density-functional theory for the electrons with the semiclassical ring-polymer instanton approximation for the nuclei. We show that the double intramolecular hydrogen transfer (DHT) rate can be enhanced by orders of magnitude due to surface fluctuations in the deep-tunneling regime. We also explain the origin of an Arrhenius temperature dependence of the rate below T_{c} and why this dependence differs at different surfaces. We propose a simple model to rationalize the temperature dependence of DHT rates spanning diverse fcc [110] surfaces.
负载型分子开关结构中氢转移反应的核隧穿交叉温度（(T_{c})）可能接近室温。这就要求即使在高温下计算反应速率时也要考虑核量子效应（NQEs）。然而，在这些环境中，依靠标准参数化降维模型计算核量子效应很快就变得不够用了。在本信函中，我们通过全维计算研究了基于吸附在金属表面的卟并苯分子的典型分子开关，该计算将电子的密度泛函理论与原子核的半经典环聚合物瞬子近似相结合。我们表明，在深隧穿区域，由于表面波动，双分子内氢转移（DHT）速率可提高几个数量级。我们还解释了低于(T_{c})时速率的阿仑尼乌斯温度依赖性的起源，以及为什么这种依赖性在不同表面有所不同。我们提出了一个简单模型来合理化跨越不同面心立方[110]表面的DHT速率的温度依赖性。
