Calculate total force on a group

Dear all
I am a new lammps user
how i can Calculate total force on a group (under the plate)? my
problem is imact two deformable part, i was created a region and group
a Small area under plate
How to i Write the Keywords?
This is my code but it has an error:

region FORCED block 0 100 0 100 0 10 units box

group FORCED region FORCED
compute force all force sum
thermo_style fz

best regard



compute property/atom command — LAMMPS documentation
Description. Define a computation that simply stores atom attributes for each atom in the group. This is useful so that the values can be used by other output commands that take computes as inputs. See for example, the compute reduce, fix ave/atom, fix ave/histo, fix ave/chunk, and atom-style variable commands… The list of possible attributes is the same as that used by the dump custom …

to first get the per atom force and then use compute reduce on your per atom compute to get the sum on the group:

It seems that you can use fcm (…) (see varibale command)