[lammps-users] NPT ensemble showing constant volume


The attached script was written to determine the melting point of silicon. I am using the NPT ensemble but am not seeing any change in volume at a temperature below or above the melting point or at any temperature. I am trying to find the Gibbs free energy for the solid and liquid phases at various temperatures to ultimately calculate the melting point. Could someone let me know what I am doing wrong?


in.SiliconMP (514 Bytes)

You are running for 10 timesteps when your NPT damping constant
for volume is 200 psec. You have also set the timestep to
0.3 psec which is far too large. Please read about LAMMPS metal
units and the fix NPT command.