Kundu Arpan, Song Yunxiang, Galli Giulia
Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637.
Department of Physics, University of Chicago, Chicago, IL 60637.
Proc Natl Acad Sci U S A. 2022 Aug 2;119(31):e2203083119. doi: 10.1073/pnas.2203083119. Epub 2022 Jul 15.
We carry out quantum simulations to study the physical properties of diamond-like amorphous carbon by coupling first-principles molecular dynamics with a quantum thermostat, and we analyze multiple samples representative of different defective sites present in the disordered network. We show that quantum vibronic coupling is critical in determining the electronic properties of the system, in particular its electronic and mobility gaps, while it has a moderate influence on the structural properties. We find that despite localized electronic states near the Fermi level, the quantum nature of the nuclear motion leads to a renormalization of the electronic gap surprisingly similar to that found in crystalline diamond. We also discuss the notable influence of nuclear quantum effects on band-like and variable-hopping mechanisms contributing to electrical conduction. Our calculations indicate that methods often used to evaluate electron-phonon coupling in ordered solids are inaccurate to study the electronic and transport properties of amorphous semiconductors composed of light atoms.
我们通过将第一性原理分子动力学与量子恒温器相结合来进行量子模拟，以研究类金刚石非晶碳的物理性质，并分析了无序网络中存在的不同缺陷位点的多个代表性样本。我们表明，量子振动耦合对于确定系统的电子性质至关重要，特别是其电子能隙和迁移率能隙，而对结构性质的影响适中。我们发现，尽管费米能级附近存在局域电子态，但核运动的量子性质导致电子能隙的重整化，这与在晶体金刚石中发现的情况惊人地相似。我们还讨论了核量子效应对有助于导电的带状和变程跳跃机制的显著影响。我们的计算表明，常用于评估有序固体中电子 - 声子耦合的方法对于研究由轻原子组成的非晶半导体的电子和输运性质是不准确的。
