First-Principles Atomic Force Microscopy Image Simulations with Density Embedding Theory.

Area of Science:

• Computational Physics
• Materials Science
• Surface Science

Background:

• Simulating noncontact atomic force microscopy (nc-AFM) requires significant computational resources.
• Accurate simulation of tip-sample interactions is crucial for interpreting nc-AFM images.
• Existing methods often involve high computational load for first-principles simulations.

Purpose of the Study:

• To present an efficient first-principles method for simulating nc-AFM images.
• To reduce the computational cost of nc-AFM simulations.
• To validate the accuracy of the proposed method against established techniques and experimental data.

Main Methods:

• Utilizing "frozen density" embedding theory to model the tip-sample interaction.
• Treating the sample as a frozen external field to simplify calculations.
• Focusing computational efforts on the tip rather than the entire tip-sample system.

Main Results:

• The simulation method accurately reproduces full density functional theory (DFT) simulations for freestanding molecules.
• Computational time is significantly reduced compared to traditional methods.
• The method successfully captures substrate electronic effects on nc-AFM images and reproduces experimental data for surface adsorbates.

Conclusions:

• The frozen density embedding theory offers an efficient and accurate approach for first-principles nc-AFM simulations.
• This method is applicable to a wide range of systems, including large molecules, 2D materials, and material surfaces.
• The approach provides a valuable tool for theoretical imaging and materials characterization.