[lammps-users] boundary style and thermo-press

Dear Steve and all other lammps users,

when I set the boundary style to be "f " , I output the thermo_press[3], but some "lost atoms" error occurs.
after the boundary style was set to be "s", there was no error. but the thermo_press I get is something different with that when boundary style is "f"

in lammps manual, the thermo_press is defined to be

I am wondering when the boundary style has been changed, is there volume change during the simulation. if not , why the thermo_press[3] are different for two boundary style.
my output script is :
fix 2 all ave/time 2 20 100 c_thermo_press[3] file stress.all

boundary style is
boundary f f f
boundary s s s

thank you

L i Ming


Read the doc page for the boundary command. F and s are different,
and thus the volume of the sys can be different and thus the pressure
can be different. If you use 'f' and atoms go outside the boundary,
you will lose them.