Farahvash Ardavan, Willard Adam P
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.
Proc Natl Acad Sci U S A. 2024 Jul 30;121(31):e2400589121. doi: 10.1073/pnas.2400589121. Epub 2024 Jul 25.
In this manuscript, we provide a general theory for how surface phonons couple to molecular adsorbates. Our theory maps the extended dynamics of a surface's atomic vibrational motions to a generalized Langevin equation, and by doing so captures these dynamics in a single quantity: the non-Markovian friction. The different frequency components of this friction are the phonon modes of the surface slab weighted by their coupling to the adsorbate degrees of freedom. Using this formalism, we demonstrate that physisorbed species couple primarily to acoustic phonons while chemisorbed species couple to dispersionless local vibrations. We subsequently derive equations for phonon-adjusted reaction rates using transition state theory and demonstrate that these corrections improve agreement with experimental results for CO desorption rates from Pt(111).
在本手稿中，我们提供了一个关于表面声子如何与分子吸附质耦合的通用理论。我们的理论将表面原子振动运动的扩展动力学映射到一个广义朗之万方程，通过这样做，将这些动力学捕获在一个单一的量中：非马尔可夫摩擦。这种摩擦的不同频率分量是由表面平板与吸附质自由度的耦合加权的声子模式。使用这种形式体系，我们证明物理吸附物种主要与声学声子耦合，而化学吸附物种与无色散的局部振动耦合。随后，我们使用过渡态理论推导了声子调整反应速率的方程，并证明这些修正提高了与Pt(111)表面CO脱附速率实验结果的一致性。
