I recently upgraded to the May 21 version of LAMMPS from a January 2008 version and found that the same set of 4 commands noted on http://lammps.sandia.gov/doc/compute_stress_atom.html:
compute peratom all stress/atom
compute p all sum c_peratom c_peratom c_peratom
variable press equal -(c_p+c_p+c_p)/(3*vol)
thermo_style custom step temp etotal press v_press
Give the following error when we try to execute using the same input file that works without any problems with the January version of the code:
"ERROR: Invalid compute style"
Has something changed in the new version (May 21) of LAMMPS that the syntax of the commands need to be changed or might something else be going on?