Department of Physics of Complex Systems, Eötvös Loránd University, Egyetem tér 1-3., H-1053 Budapest, Hungary.
Departamento de Física Aplicada I, Universidad de Sevilla, E-41012 Seville, Spain.
J Phys Chem B. 2023 Mar 2;127(8):1728-1734. doi: 10.1021/acs.jpcb.2c07946. Epub 2023 Feb 15.
The finding that electronic conductance across ultrathin protein films between metallic electrodes remains nearly constant from room temperature to just a few degrees Kelvin has posed a challenge. We show that a model based on a generalized Landauer formula explains the nearly constant conductance and predicts an Arrhenius-like dependence for low temperatures. A critical aspect of the model is that the relevant activation energy for conductance is either the difference between the HOMO and HOMO-1 or the LUMO+1 and LUMO energies instead of the HOMO-LUMO gap of the proteins. Analysis of experimental data confirms the Arrhenius-like law and allows us to extract the activation energies. We then calculate the energy differences with advanced DFT methods for proteins used in the experiments. Our main result is that the experimental and theoretical activation energies for these three different proteins and three differently prepared solid-state junctions match nearly perfectly, implying the mechanism's validity.
研究发现，在金属电极之间的超薄蛋白质膜中，电子电导从室温到只有几度开尔文几乎保持不变，这一发现带来了挑战。我们表明，基于广义的 Landauer 公式的模型可以解释这种近乎恒定的电导，并预测低温下类似于 Arrhenius 的依赖关系。该模型的一个关键方面是，对于电导来说，相关的激活能是 HOMO 和 HOMO-1 之间的差异，或者是 LUMO+1 和 LUMO 之间的能量，而不是蛋白质的 HOMO-LUMO 能隙。对实验数据的分析证实了类似于 Arrhenius 的定律，并允许我们提取激活能。然后，我们使用实验中使用的蛋白质的高级 DFT 方法计算能量差异。我们的主要结果是，这三种不同的蛋白质和三种不同制备的固态结的实验和理论激活能几乎完全匹配，这意味着该机制的有效性。
