# Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study

## TL;DR

This paper presents a first-principles method combining DFT and experimental data to accurately simulate STM images of copper adatoms and CO molecules on Cu(111), enhancing interpretation of experimental results.

## Contribution

It introduces a novel computational approach for simulating STM images that integrates DFT calculations with experimental AFM data for detailed analysis.

## Key findings

- Calculated STM images agree with experimental results
- Method accurately determines tip apex atomic structure
- Enhanced interpretation of STM images achieved

## Abstract

We describe a first principles method to calculate scanning tunneling microscopy (STM) images, and compare the results to well-characterized experiments combining STM with atomic force microscopy (AFM). The theory is based on density functional theory (DFT) with a localized basis set, where the wave functions in the vacuum gap are computed by propagating the localized-basis wave functions into the gap using a real-space grid. Constant-height STM images are computed using Bardeen's approximation method, including averaging over the reciprocal space. We consider copper adatoms and single CO molecules adsorbed on Cu(111), scanned with a single-atom copper tip with and without CO functionalization. The calculated images agree with state-of-the-art experiments, where the atomic structure of the tip apex is determined by AFM. The comparison further allows for detailed interpretation of the STM images.