Yoshimura Anthony, Lamparski Michael, Giedt Joel, Lingerfelt David, Jakowski Jacek, Ganesh Panchapakesan, Yu Tao, Sumpter Bobby G, Meunier Vincent
Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Nanoscale. 2023 Jan 19;15(3):1053-1067. doi: 10.1039/d2nr01018f.
Many computational models have been developed to predict the rates of atomic displacements in two-dimensional (2D) materials under electron beam irradiation. However, these models often drastically underestimate the displacement rates in 2D insulators, in which beam-induced electronic excitations can reduce the binding energies of the irradiated atoms. This bond softening leads to a qualitative disagreement between theory and experiment, in that substantial sputtering is experimentally observed at beam energies deemed far too small to drive atomic dislocation by many current models. To address these theoretical shortcomings, this paper develops a first-principles method to calculate the probability of beam-induced electronic excitations by coupling quantum electrodynamics (QED) scattering amplitudes to density functional theory (DFT) single-particle orbitals. The presented theory then explicitly considers the effect of these electronic excitations on the sputtering cross section. Applying this method to 2D hexagonal BN and MoS significantly increases their calculated sputtering cross sections and correctly yields appreciable sputtering rates at beam energies previously predicted to leave the crystals intact. The proposed QED-DFT approach can be easily extended to describe a rich variety of beam-driven phenomena in any crystalline material.
已经开发了许多计算模型来预测二维（2D）材料在电子束辐照下的原子位移速率。然而，这些模型往往严重低估了二维绝缘体中的位移速率，在二维绝缘体中，束流诱导的电子激发会降低被辐照原子的结合能。这种键软化导致理论与实验之间存在定性分歧，即实验观察到在许多当前模型认为远太小而无法驱动原子位错的束流能量下会发生大量溅射。为了解决这些理论缺陷，本文开发了一种第一性原理方法，通过将量子电动力学（QED）散射振幅与密度泛函理论（DFT）单粒子轨道耦合来计算束流诱导电子激发的概率。所提出的理论随后明确考虑了这些电子激发对溅射截面的影响。将该方法应用于二维六方氮化硼和二硫化钼，显著增加了它们计算出的溅射截面，并正确地在先前预测会使晶体保持完整的束流能量下产生了可观的溅射速率。所提出的QED-DFT方法可以很容易地扩展，以描述任何晶体材料中丰富多样的束流驱动现象。
