Dear all,

I am writing this letter for how to calculate the contact area.

In our MD studies, we use flat diamond sample and spherical tip made of diamond-like carbon which is rigid and fractal rough.

I plant to calculate the contact area use the “compute group/group” command, but only pair wise interactions are included in this calculation and 3-body potentials, such as airebo potential, cannot be used.

Then, some colleagues proposed the method of setting cutoff radius. For example, the radius of the indenter is r_{0} and the cutoff radius is r(r is greater than r_{0}).Thus, the atoms of the sample which is in the cutoff radius is defined as “contact atoms”. However, I am not sure that the method of setting cutoff radius is suitable for the indenter with fractal roughness. I am afraid of the ineffective of characterizing the fractal roughness.

Would you be so kind to tell me your advice about it? I wonder if you could help me compile additional fix style which could calculate the contact area about my model and link to the Lammps.Thanks!

Haidong,Lei