Hooke with fix rigid/small molecule

Hello LAMMPS users,

I am investigating the use of Hooke potential with fix rigid small as
per the example provided below. Could you please help/point me to some
documentation or information to do so?

units lj
dimension 3
boundary p p p
atom_style full

read_data initpos.dat
group big type 1
group wall type 2

mass 1 1.0
mass 2 20.0

velocity big set 0.0 0.0 -0.03 units box

pair_style lj/cut 1.25

pair_coeff 1 1 1.0 0.8 0.9
pair_coeff 1 2 1.0 2.0 2.24
pair_coeff 2 2 0.0 1.0

neigh_modify exclude molecule/intra big

neighbor 0.2 bin
neigh_modify delay 0

fix blocca big rigid/small molecule

compute tke big ke/rigid blocca
compute rke big erotate/rigid blocca
compute tke2 wall ke

timestep 0.05
dump 1 all xyz 5000 gra.xyz

thermo 100
thermo_style custom step c_tke c_rke c_tke2 lx ly

run 20000

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There is not enough information here to give some specific advice. What features are available in LAMMPS is documented in the manual. It is big, but there are options to search it (via google). Nobody is likely to do what is effectively your job for you.