[lammps-users] simulation box and simulation cell

dear all, when i learn LAMMPS and MD,i always am confused by
simulation box or simulation cell . are they same? i believe that
simulation box is geometry without the atoms, while the simulation
cell is constituted by real atoms. so boundary command is applied to
simulation box not simulation cell. if i want to apply real boundary
to real atoms,i must find other operation, isn't it? i am appreciated
for your advices. p.S.,i want to know how to compute the volume of
simulation box or simulation cell, and the volume in dump command is
equal to box or cell? so i want to know how to computer the press
in dump command. when i want to control the press ,how the press is
relate to the volume? many thanks.

LAMMPS doesn't typically refer to simulation cell. The simulation
box is what the volume is computed on, whether it is filled
with atoms or not.