How to select the atom_style for fix rigid command

Hi everyone
i am currently trying to use fix rigid to create rigid body to simulate the shape effect.
I used

fix         11 all rigid/nve/small molecule
compute t1 all temp/sphere
thermo_modify temp t1
fix         9 all press/berendsen x ${pstart} ${pend} ${pdamp} y ${pstart} ${pend} ${pdamp} z ${pstart} ${pend} ${pdamp}

therefore, my data file have the column of molecule, since my rigid body is made of small spherical grain, i therefore use the

atom_style      sphere

but i got the error
Incorrect format in Atoms section of data file, i can see this problem is caused by the column of molecule, so what should we use when we only have rigid body (made of spherical grains).

besides, what we should do if we have mixtures,saying bpm package created clump and rigid body?
should we use bpm/sphere since this larger than atom_style sphere?

many thanks for the help, hope someone is happy for sharing any idea

You need a way to have both, density and diameter as with pair style sphere, and molecule ID as with pair style bond, angle, or molecular. This can be done either by using atom style hybrid or fix property/atom mol. For details, please see the documentation of the atom_style, fix property/atom and read_data commands.

Hi akohlmey

many thanks for your help and reponse, i will try to read these documentation carefully, and try to see whether i can identify the way to achieve my target

thanks for your time and hope you have a nice day

best regards