Dear all,

I’m using LAMMPS to do tensile simulations. I found that the p_tensor is equal to the summation of ke_tensor and virial terms (as described in pressure.cpp), where ke_tensor is computed only from the velocity of all atoms (in temp_full.cpp) and the virial term is always equal to zero. However, the stress tensor is computed from the atomic velocity and force, that is, S(a,b) = - mv(a)v(b)+0.5*sum{[a(i)-a(j)]Fb(i,j);j=1,n} (in fix_stress.cpp). Now, I’m wondering that how we can draw the conclusion that “Also note that this quantity is the negative of the per-atom pressure tensor.” (in the help file dump.html). Could anyone explain this to me? thanks.
In addition, I want to compute the stress as S(a,b) = 0.5*sum{[a(i)-a(j)]Fb(i,j);j=1,n}, are there many codes need to be modified and where are they? Any suggestion is appreciated.

With best regards,

ZHENG

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