Dear lammps users,
I have a question about “fix_modify energy yes” command. To understand this, I did a test:
I have a copper bulk, then i apply a force by “fix addforce” command, if I use only fix addforce, then it can finish within 1 step and configuration did not change; then with same input file and initial model, i only add one more command by “fix_modify energy yes” then, it takes 30 steps to finish and the bulk is stretched. With modified energy. it looks like force have effect on our model. In conclusion, if I want to study the applied constant force effect of my model and calculate the actual stress of the model, then i definitely should add this “fix_modify” command, is this the case? Without this command, even though we use “fix addforce”, the load is actually not applied on the model, am I correct?
Another question, in this study, does lammps code assume the calculated stress is about equal to the applied force since the minimization is under equilibrium state.
Thank you so much for your comments.