Very rare non-numeric pressure due to atom overlaps?

[akohlmey]

@Yura_Polyachenko

physically have LJ repulsion so I set corresponding \epsilon_{i,j} = 0ϵi,j=0\epsilon_{i,j} = 0 and arbitrary \sigma_{i,j}=1σi,j=1\sigma_{i,j}=1. r_{c,i,j}=2^{1/6} \sigma_{i,j}rc,i,j=21/6σi,jr_{c,i,j}=2^{1/6} \sigma_{i,j} for all pairs.

Since you are using hybrid/overlay, you could just not have the lj/cut pair style be applied to those pairs.

@Yura_Polyachenko

Can an exact overlap of 2 atoms (float(r1) == float(r2)) which formally have an LJ potential but also have \epsilon=0ϵ=0\epsilon=0 cause a “non-numeric pressure” crash

Yes, because you need to divide by this (squared) distance.

@Yura_Polyachenko

interactions with \epsilon=0ϵ=0\epsilon=0 are excluded from evaluation?

No they are included, if they are listed under pair_coeff.

@Yura_Polyachenko

If \epsilon=0ϵ=0\epsilon=0 are not excluded, is there a way to tell lammps not to evaluate specific pair_style-s (from a hybrid style) for specific type-pairs?

Yes, with hybrid/overlay you can just not define pair_coeff for lj/cut for those pairs. With regular hybrid, you can use pair_coeff none and with plain lj/cut you can set the cutoff to 0 or you could use neigh_modify exclude.