Efficient method for fast simulation of scanning tunneling microscopy with a tip effect.

Area of Science:

• Surface Science
• Computational Materials Science
• Scanning Tunneling Microscopy

Background:

• Electron tunneling is fundamental to scanning tunneling microscopy (STM) operation.
• Accurate simulation of STM images requires efficient and reliable theoretical methods.
• Existing methods, like Paz et al.'s, have limitations in computational efficiency and parameterization.

Purpose of the Study:

• To develop a novel, computationally efficient method for simulating STM images.
• To provide an improved approach for calculating the tunneling current between an STM tip and a sample.
• To enable accurate STM image simulation using first-principles computing software.

Main Methods:

• Derived a new expression for tunneling current based on Bardeen's perturbation theory.
• Utilized fast Fourier transform (FFT) for efficient calculation of the tunneling integral.
• Implemented the method within first-principles computing frameworks, using independent wave functions of tip and sample.

Main Results:

• The developed method demonstrates high computing efficiency and fewer parameters compared to previous approaches.
• Simulated STM images for benchmark systems (H-H, Pd2-Ag2) show good agreement with theoretical expectations.
• Topographic images of CO on Cu(111) using different tips closely matched experimental data.

Conclusions:

• The new method offers a computationally inexpensive and accurate way to simulate STM images.
• It provides a practical tool for researchers using first-principles calculations and STM.
• The approach yields more reasonable simulated results at a lower computational cost.