Kindly assist with my challenge. I used stress/atom commands in LAMMPS to calculate Von miss stress and hydrostatic stress of a silicon nanometric cutting. Unfortunately or fortunately I got hydrostatic stress of maximum -3GPa and 1GPa which is low compared to 11GPa - 14GPa for Si and diamond tool with 204241 atoms. Note, the hydrostatic stress is for tool atoms group. I attached the stress part of the script. If there is a need to attach the entire script, I will.
IYH Dear Tirimisiyu Olaniyan
Many root causes are possible.
IHMO as a first step kindly visualize the stress distribution in the tool atoms group w OVITO or some such tool to see if there are any patterns or anomalies that could explain the low hydrostatic stress values. Why? Consider the possibility of a non-uniform stress distribution in the tool atoms group. The hydrostatic stress may vary across different regions of the group, leading to a lower overall value.
More mundane (I've committed such snafus many times :D), but pays to double check:
Set error / warning verbosity level to 1000 in the LAMMPS output. eg
-echo screen 1000 -log 1000
This will ensure that all error and warning msgs are displayed on the screen and written to the log file w detailed information about the simulation process. Look this over (and paste it in the question here just in case).
Verify the units used in the calculation. Ensure that the units are consistent and correctly converted to GPa.
Run longer (Insufficient Simulation Time): The simulation time may not be long enough for the system to reach equilibrium, leading to inaccurate stress calculations.
Numerical Accuracy: The numerical accuracy of the simulation could be a factor. Consider using a smaller time step or a more accurate integration algorithm (eg virial stress method or the Irving-Kirkwood stress method)
Daniyel Yaacov Bilar . Thanks for your insights. I will try your suggestions.