[lammps-users] Problem with reaxff, npt, volume and lattice constant

Dear Sir,

I am simulating a molecular crystal by using reaxff to determine it’s structural phase transtition from 143K to 300K. However after I am well equilibrate by using nvt and nve, when I start with npt, the volume and lattice length has high fluctuation. Which part has the problem? Is hbcut and precision will affect the data?

in.p (545 Bytes)

data1.paa (919 Bytes)

Fluctuations in pressure and hence volume are normal when
running NPT. Espcially if you have a small system. Also
especially if you start away from equilibrium. When you
run NVE or NVT are you sitting at a pressure that is close
to the target you pick for NPT? If not, you are out of