[lammps-users] difference of two command

Dear,

I want to know the difference of codes for the same system as follows,

group wall type 1
group mobile type 2

code 1:
fix 1 mobile nvt 1.0 1.0 1.0 drag 0.2

the fix does not include group wall, so does not change the velocity of the wall

code 2:

fix 1 all nvt 1.0 1.0 1.0 drag 0.2
fix 2 wall setforce 0.0 0.0 0.0 use setforce command to not change the velocity of the wall

I have test the two codes in the same script, but code 2 give a physical result, code 1 give a wrong result .

I am confused? Any suggestion, Thanks

The 2nd example will include the wall atoms
in the computation of temperature, used in the NVT
thermostat.

Steve