Kolibri Sensor Modeling

[Victor-V5]

Dear all,

I am currently using a Kolibri sensor with an unfunctionalized tungsten (W) tip for my nc-AFM experiments, and I would like to model this configuration in my simulations.

If anyone has:

Simulation parameters (e.g., force field settings, tip radius, stiffness, resonance frequency, damping, effective charge distribution, tip–sample interaction models) that have worked well for a Kolibri sensor with an unfunctionalized W tip,

References to published work where such parameters are reported or discussed,

Or recommendations on best practices for setting up this kind of simulation,

I would greatly appreciate if you could share them.

Thank you very much in advance for your help!

Best regards,
Victor Vaillant

[ondrejkrejci]

Hi Victor!

Thank you for the question!
I am afraid, that unfunctionalized tungsten tip is something, that this model is not capable of. While moving from Qplus to Collibry is an easy task of setting two parameters differently. The model is developed for functionalized tips terminated by a single atom. This functionalizations has 2-3 effects - all the contrast is determined only by a short range interaction with the last atom of the tip and this interaction is only weak i.e. van der Waals, with London dispersion and electrostatic dominated in a far-away regime (but really close to the samle, so one have atomic resolution) and Pauli repulsion dominated in the close regime. Also the last atom is mostly flexible, especially in x and y direction.

For the W tip, you are not considering a single atom, but a tip radius. And also W is very reactive, thus vdW forces are not the only driving forces there. Both of these factors are not part of our approach. Unless you can be more specific about how one can thing a single atom tip and how to remove the chemical interaction between tip and sample, then I think that you would need to find a different way, How to simulate this.

@ProkopHapala - do you want to maybe add something?

With kind regards,
Ondrej