Molecular dynamics simulation of bimodal atomic force microscopy.

Area of Science:

• Surface science
• Atomic force microscopy
• Computational physics

Background:

• Bimodal atomic force microscopy (AFM) enables simultaneous acquisition of surface morphology and properties.
• Observing atomic-scale phenomena in bimodal AFM vibrations is challenging due to the lack of suitable models.

Purpose of the Study:

• To develop an atomic-scale model for bimodal AFM.
• To simulate and observe atomic phenomena during cantilever vibrations in bimodal AFM.
• To analyze tip-substrate interactions at the atomic level.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model bimodal AFM.
• Employed a double springs oscillator model for the AFM cantilever's first two vibration modes.
• Applied dual-frequency excitation to observe tip dynamics and interactions.

Main Results:

• The MD simulations successfully modeled bimodal AFM at the atomic scale.
• Observed tip dynamics and tip-substrate interactions under dual-frequency excitation.
• Simulation results for amplitude, phase shift, and average force changes align with continuum models and experimental data.

Conclusions:

• The developed MD model provides a novel approach for simulating bimodal AFM at the atomic scale.
• This model facilitates the study of atomic-scale phenomena in bimodal AFM vibrations.
• The findings enhance understanding of tip-sample interactions for advanced surface characterization.