Dear Lammps Users,
I am simulating a crystal periodic in two directions that is x and y and non periodic in z. I am using NVT for equilibrating the crystal at 300 K. I observe that Pzz fluctuates around zero which is expected as there is vacuum above and below the crystal in z direction. But Pxx and Pyy are as high as 20000 bars when NVT ensemble is used.
I thought the crystal will expand (to achieve mechanical equilibration) and pressure will be zero during equilibration. But I get a very high value of pressure Is there a physical reason why crystal is not expanding or is the pressure calculation not correct?
I would be very thankful if someone can help me to clarify my doubt.