Duan Sai, Tian Guangjun, Xu Xin
Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, MOE Key Laboratory of Computational Physical Sciences, Department of Chemistry, Fudan University, Shanghai200433, P. R. China.
Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
JACS Au. 2022 Dec 30;3(1):86-92. doi: 10.1021/jacsau.2c00627. eCollection 2023 Jan 23.
Scanning tunneling microscopy (STM) is one of the most popular techniques for precise characterization. Yet, its current theoretical implementation is often based on the periodic boundary condition with the Tersoff-Hamann approximation, which is inefficient to explore the tip states other than the -wave and to treat properly the charged molecules that are ubiquitous in chemistry. In this work, we establish a general theoretical framework for STM image simulations, which is based on the Bardeen's approximation and utilizes the boundary condition of the cluster model. We develop an analytic algorithm for the precise evaluation of the transfer Hamiltonian matrix, addressing correctly the asymptotic behaviors of the tip states. Numerical results demonstrate that the molecular images under different STM tip states and mapping modes can be quantitatively simulated in the present framework, which paves the avenue for the conclusive investigation of the ground state electronic structures for either neutral or charged molecules.
扫描隧道显微镜（STM）是最常用的精确表征技术之一。然而，其当前的理论实现通常基于具有特罗菲-哈曼近似的周期性边界条件，这种方法在探索除s波之外的尖端态以及正确处理化学中普遍存在的带电分子时效率低下。在这项工作中，我们基于巴丁近似建立了一个用于STM图像模拟的通用理论框架，并利用团簇模型的边界条件。我们开发了一种用于精确评估转移哈密顿矩阵的解析算法，正确地处理了尖端态的渐近行为。数值结果表明，在当前框架下可以定量模拟不同STM尖端态和映射模式下的分子图像，这为确定性研究中性或带电分子的基态电子结构铺平了道路。
