Dear LAMMPS users,
Based on the description of compute_pressure, the virial part will be the summation of Fi_dot_ri, where Fi is the net force on atom i and ri is the location of atom i.
Based on this description, I have a question about how ri is defined.
Is ri the absolute location of atom i or there is a reference origin?
If ri is the absolute location of atom i, based on the definition, will the pressure change if we have two systems at same status (assuming same Fi for atoms) but with different spatial location (translational offset)?
Thanks!
Dear LAMMPS users,
Based on the description of compute_pressure, the virial part will be the
summation of Fi_dot_ri, where Fi is the net force on atom i and ri is the
location of atom i.
Based on this description, I have a question about how ri is defined.
Is ri the absolute location of atom i or there is a reference origin?
r_i is the absolute location.
If ri is the absolute location of atom i, based on the definition, will the
pressure change if we have two systems at same status (assuming same Fi for
atoms) but with different spatial location (translational offset)?
no. please recall, that all force contributions can be decomposed into
pairwise contributions.
for each pair ij, the virial contribution becomes: F_ij dot r_i +
-F_ij dot r_j = F_ij dot (r_i - r_j). and (r_i - r_j) is invariant to
translation of the entire system.
axel.