Hybrid pair potential

I am simulating a composite system- Medium entropy alloy reinforced by nanodiamond particle. I used “meam” for Medium entropy alloy particles & AIREBO for nanodiamond & lj/cut for VAN DAR WAALS interaction force between metals & carbon atoms.
Medium entropy alloy (used here) melting temperature= 2273 K.
diamond melting temperature= 3655k.
but when sintering, my diamond particle melts before MEA particle. I just want to make sure whether my interatomic pair potential is correctly written.

group V type 1
group Nb type 2
group Ta type 3
group Ti type 4
group Zr type 5
group C type 6

pair_style hybrid meam airebo 3 lj/cut 3
pair_coeff * * meam library_VNbTaTiZr.meam V Nb Ta Ti Zr VNbTaTiZr.meam V Nb Ta Ti Zr NULL
pair_coeff * * airebo CH.airebo NULL NULL NULL NULL NULL C
pair_coeff 1 6 lj/cut .055 2.934 3
pair_coeff 2 6 lj/cut .064 3.06 3
pair_coeff 3 6 lj/cut .08 3.06 3
pair_coeff 4 6 lj/cut .051 3.058 3
pair_coeff 5 6 lj/cut .058 3.182 3

The code below will trigger an error since “morse” is not listed as a hybrid sub-style.

This line makes no sense, anyway, since it will wipe out the preceding line with the airebo potential.

Why a cutoff of 3 angstrom? That is shorter than even the minimum of the LJ potentials in your input.

My apology…edited.
Communication cut-off was adjusted 6.3 by LAMMPS.
Btw,Catbon nano diamond size=11 Angstrom (rad)
HEA particle size=25 Angstrom (rad)
Does size have an impact on sintering of composite?
And is pair potential correct now??

That doesn’t change the cutoff on the pair styles.

That is for you to find out from the published literature since this is your research.

The input is syntactically correct. That is all I can say. As mentioned about the LJ cutoff makes no sense, but it is not likely to have much impact on your observations.

Whether this is a meaningful model and whether the potential parameters and settings are suitable for your purpose cannot be said from remote. Again, this is part of your research and thus it is your job to ascertain that the potentials you are using are suitable for the materials and conditions you are using them for from the publications describing them (or other publications using and confirming the suitability).

Besides, what are you putting in your paper to justify your choices? “Some guy in the LAMMPS forum said it was OK to use this.”?? How do you think this will look?

Dear, thanks for your reply.
I’ll change cut-off of both AIREBO & lj/cut.
From several publications, I came to know that It’s appropriate to use AIREBO/TERSOFF for nanodiamond/graphene/Carbon nanotube. But as my nanodiamond was melting at 1800k, I posted about the correctness of my pair potential because there are some restriction for hybrid pair potential.

The choice for AIREBO was correct. In fact, anything other than using 3.0 would be a problem.

You are neglecting the conditions and are not properly appreciating the properties and limitations of the model you are setting up. Classical potentials like they are used in LAMMPS have limited transferability. So if something is giving a reasonably good match at ambient temperature and pressure, that is no confirmation that the same parameterization/potential is suitable for elevated temperatures (or very low temperatures) or high pressures. In some cases, potentials can be used for bulk but not for nanoparticles.

But those apply primarily to the interaction between the different sub-styles of the hybrid potential. What you are describing seems to be (mostly) independent of that.

… and again, a syntactically correct input is no guarantee for correct results and the validity of potentials cannot be confirmed from the outside. That requires testing and a more thorough review of the published literature than you seem to have done.

Sorry, but there ain’t no escape from the blues. If you want to be certain that something is correct, you have to do the work and run tests and review as much relevant literature as you can get your hands on.

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