Efficient Method for Fast Simulation of Scanning Tunneling Microscopy with a Tip Effect
Efficient Method for Fast Simulation of Scanning Tunneling Microscopy with a Tip Effect
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具有尖端效应的扫描隧道显微镜快速模拟的有效方法
DOI：
10.1021/jp5018218
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发表时间：
2014
影响因子：
2.9
通讯作者：
Yang Jinlong
中科院分区：
文献类型：
--
作者：
Zhang Ruiqi;Hu Zhenpeng;Li Bin;Yang Jinlong
在Bardeen的电子隧穿微扰理论的基础上，受Paz等人S研究的启发，得到了扫描隧道显微镜针尖与样品之间隧道电流的新表达式，为模拟扫描隧道显微镜图像提供了一种有效的方法。该方法可以在第一原理计算软件的任何代码中实现，该软件提供在相同基础上独立计算的尖端和样品的波函数作为输入。利用快速傅立叶变换(FFT)进行积分计算，在PC机上用不同类型的数据库模拟给定样品表面的STM图像，并不是一件费时的工作。与Paz等人的S方法相比，该方法摒弃了真空格林函数的应用，具有更高的计算效率、更少的参数和更合理的模拟结果，特别是在计算成本更低的情况下。以H-H和PD2-AG2等简单的TIP-Sample系统为基准对该方法进行了测试。还模拟了用钨针尖和CO末端针尖在铜(111)面上吸附的CO分子的形貌图像，模拟结果与实验结果吻合较好。
On the basis of Bardeen’s perturbation theory on electron tunneling and inspired by Paz et al.’s study, a new expression for the tunneling current between the scanning tunneling microscopy (STM) tip and sample has been obtained, and it provides us with an efficient method to simulate STM images. The method can be implemented in any code of first-principles computing software, which offers the wave functions of the tip and sample, calculated independently at the same footing, as input. By calculating the integral with fast Fourier transform (FFT), simulating the STM image of a given sample surface by a database of different tips on a PC turns out to be not a time-consuming work. Compared with Paz et al.’s method, our method abandons the application of the vacuum Green function and possesses better computing efficiency, fewer parameters, and more reasonable simulated results especially at lower computing cost. Simple tip–sample systems, such as H–H and Pd2–Ag2, are taken as benchmarks to test our method. The topographic images of a CO molecule adsorbed on a Cu(111) surface obtained by using a tungsten tip and a CO-terminated tip are also simulated, and the simulated results are in good agreement with the experimental ones.