Hello Everyone,

I have been trying to run a GCMC simulation for adsorption of N2 in MOF-5, but no matter how long I run the simulation gcmc insertion success is always zero (Which is obviously wrong). I have tried changing N, X, M parameters in the fix gcmc command but no avail. Can someone please help me with this? The exact same simulation works well with RASPA but it is very slow as multithreading or more than 1 MPI processes are not permitted in RASPA. Attaching the relevant simulation files along with this post. (For some reason I am not able to attach the file, so copy pasting the input file here. Sorry about this.)

```
##################
# INITIALIZATION #
##################
units real
atom_style full
dimension 3
newton on
boundary p p p
pair_style lj/cut/coul/long 12.5
bond_style harmonic
angle_style hybrid fourier cosine/periodic harmonic
dihedral_style harmonic
improper_style fourier
kspace_style ewald 1e-06
pair_modify shift yes tail no mix arithmetic #shifted, tail correction no, lorentz bertholt mixing rule
special_bonds lj/coul 0.0 0.0 1.0
dielectric 1.0
box tilt large
#n2 not in the file, so to add this extra/... stuff is there
read_data data.IRMOF-1.lammps &
extra/atom/types 2 &
extra/bond/types 1 &
extra/angle/types 1
molecule n2mol n2.mol.lammps #n2 molecule file traPPE model
#replicate 2 2 2 #create a 2*2*2 unit cell
#create_atoms 0 random ${N_n2} 2345243 NULL mol n2mol 534556
mass 6 1e-20
mass 7 14.05
pair_coeff 6 6 0 0 #pair_coeff type type epsilon(energy units, here kcal/mol) sigma (distance units, here Angstrom)
pair_coeff 7 7 36.00 3.31
bond_coeff 7 0 0.55
angle_coeff 10 harmonic 0 180
# GROUPS
group n2 type 6 7 #Group definition of n2 molecule
group fram type 1 2 3 4 5 #Group definition of Framework
############
# SETTINGS #
############
reset_timestep 0
neighbor 2.0 bin
neigh_modify every 1 delay 10 check yes
#min_style cg
#minimize 0.0 1e-08 100000 10000000
#run 0
variable nAds equal count(n2)/3
variable dt equal dt
variable tdamp equal ${dt}*100
variable pdamp equal ${dt}*1000
compute mdtemp n2 temp
compute_modify mdtemp dynamic/dof yes
#fix 1 all npt temp 313.15 313.15 ${tdamp} iso 45 45 ${pdamp}
velocity all create 77 2435728
#thermo 500
#timestep 1
#run 10000
#unfix 1
#write_data dataAfterNPT.data
fix 2 n2 gcmc 10 100 100 0 342134 77 0 0.5 pressure 0.1 mol n2mol group n2
#fix 3 all nvt temp 313.15 313.15 ${tdamp}
thermo 100
thermo_style custom step v_nAds press temp f_2[3] f_2[4] f_2[5] f_2[6]
timestep 1
run 200000
```