I’m a newcomer in using LAMMPS, and have just simulated the melting of Pt nanoparticles, and when chosing NVE or NVT ensembles, the project goes well ,but once I chose the NPT ensemble, the program would stop. The error is " the thermodynamics detects the lost atoms", I don’t know what does it mean?
The parameters you’ve chosen for your NPT thermostat have probably induced huge volume changes that result in unrealistic dynamics, overlapping atoms, and lost atoms, which causes LAMMPS to stop.
Try a larger value for the Pdamp constant of fix npt (see this page: http://lammps.sandia.gov/doc/fix_npt.html ) and make sure your setpoint pressures (Px_start, etc.) make sense.