I am trying to predict the mass density of a methane system in liquid phase (e.g. 100 bar and 180 K condition). The initial configuration is generated using the VMD TopoTools plugin according to the target density. For equilibration of the system, I am going to run NVE or NVT simulations. Usually in such simulations we consider the system equilibrated when the energy or temperature is converged. But I’d like to know if I need to check the pressure as well. To me, it might be also important to see if the (average) pressure matches the desired one before going to the NPT run. Any comments and suggestions on this matter are greatly appreciated.