The difference of density between geometry optimization and dynamics simulation (NPT ensemble) in FORCITE module.

Hi, everyone,

I had a problem when calculating TATB in the FORCITE module.

When the FORCITE settings (COMPASS force field) are the same, the density of Geometric Optimization (check Optimize Cell) and molecular dynamics simulation (NPT ensemble) has obvious difference. 






Where does this difference come from? How to eliminate this difference? The result of geometric optimization is obviously closer to the theoretical value (1.938). How to adjust the error of NPT ensemble?

Thank You.