I want to obtain the stress-strain curve for a two dimensional material by applying uniaxial tension. I am relaxing the system to 300K temperature using isothermal-isobaric ensemble before introducing deformation to the simulation cell. I suppose I have to use this fix for relaxation (since the pressure unit is in Bars and temperature unit is Kelvin) -
fix NPT all npt temp 300.0 300.0 5.0 iso 1.0 1.0 5.0
However, I have found examples of this fix being used for atmospheric pressure -
fix NPT all npt temp 300.0 300.0 5.0 iso 0.0 0.0 5.0
Is it a mistake they have made? Or is the difference so negligible that the obtained output stress-strain data is identical?
Thanks in advance.