Dear Vivek,

if you use interatomic potentials and MD, you can only model the ballistic regime where ion-ion collisions are dominant. Impinging ions also loose energy by interaction with electrons (of the host). This interaction grows as a function of the energy. It is taken into account in SRIM, but not in your MD calculations.

I am not sure, but maybe an energy of 30 keV for Ga ions is high enough for electronic interactions to be significant. This may be why your MD simulations yield different results than SRIM.

Best

Laurent Pizzagalli

Dear Laurent,

Thank you for your reply.

I agree that ignoring the electron interaction in MD may be a reason behind observed anomaly at high energies.

Some nice 30kV simulations have been done previously (for example, figure 2(b) in https://www.sciencedirect.com/science/article/pii/S0167577X16314069 ) and the results corresponds to the SRIM predicted values quite accurately.

The variations might have been due to the interaction potentials (hybrid ZBL-Tersoff), and I tried Stillinger-Weber and modified Stillinger-Weber (from your paper, Article A new parametrization of the Stillinger-Weber potential for ...

Once again, many thanks for your reply. Any further feedback or suggestion in this regard is highly appreciated.

Regards,

Vivek

Dear Vivek,

so it seems there is something a bit more complicated that my too simple explanation. I think that you should contact Julien Guénolé (one author from the first reference you cited), he is a friend of mine, and very knowledgeable about these aspects. Maybe he will be helpful for your issue?

Regards,

Laurent

Dear Vivek,

it might also be useful to you to have a look at Julien Guénolé 's latest work on this type of problems. Article Atomistic simulations of focused ion beam machining of strai...

Regards,

Enrico

Dear Laurent,

Thank you for your reply. I contacted Julien earlier, and got his valuable feedback to see if lattice orientation, incidence angle, modified SW vs Tersoff potential account for such discrepancy.

Dear Enrico,

Many thanks for your reply and suggesting the reference, I have been referring to this paper. It is a nice work demonstrating MD simulations of low energies (5kV) irradiation in accordance with SRIM. My results at low energies are also in accordance with SRIM, the issue is arising at high ion energies (16-30kV).

Regards,

Vivek