Koczor-Benda Zsuzsanna, Mateeva Teodora, Rosta Edina
Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.
J Phys Chem Lett. 2023 Nov 9;14(44):9935-9942. doi: 10.1021/acs.jpclett.3c02624. Epub 2023 Oct 30.
Umbrella sampling molecular dynamics simulations are widely used to enhance sampling along the reaction coordinates of chemical reactions. The effect of the artificial bias can be removed using methods such as the dynamic weighted histogram analysis method (DHAM), which in addition to the global free energy profile also provides kinetic information about barrier-crossing rates directly from the Markov matrix. Here we present a binless formulation of DHAM that extends DHAM to high-dimensional and Hamiltonian-based biasing to allow the study of electron transfer (ET) processes, for which enhanced sampling is usually not possible based on simple geometric grounds. We show the capabilities of binless DHAM on examples such as aqueous ferrous-ferric ET and intramolecular ET in the radical anion of benzoquinone-tetrathiafulvalene-benzoquinone (Q-TTF-Q). From classical Hamiltonian-based umbrella sampling simulations and electronic coupling values from quantum chemistry calculations, binless DHAM provides ET rates for adiabatic and nonadiabatic ET reactions alike in excellent agreement with experimental results.
伞形采样分子动力学模拟被广泛用于增强沿着化学反应坐标的采样。可以使用诸如动态加权直方图分析方法（DHAM）等方法消除人工偏差的影响，该方法除了提供全局自由能分布外，还能直接从马尔可夫矩阵中提供有关势垒穿越速率的动力学信息。在此，我们提出了一种无箱式的DHAM公式，它将DHAM扩展到高维和基于哈密顿量的偏差，以允许研究电子转移（ET）过程，基于简单的几何原理，通常无法对其进行增强采样。我们通过诸如亚铁 - 铁离子在水溶液中的电子转移以及苯醌 - 四硫富瓦烯 - 苯醌（Q - TTF - Q）自由基阴离子中的分子内电子转移等示例展示了无箱式DHAM的能力。基于经典的基于哈密顿量的伞形采样模拟和量子化学计算得到的电子耦合值，无箱式DHAM为绝热和非绝热电子转移反应提供的电子转移速率与实验结果高度吻合。
