There seems to be a difference in how fix gcmc operates when hybrid vs.
non-hybrid potentials are used. In particular, the use of pair_style
hybrid causes a segmentation fault at the end of a run, and the number
of insertions and (especially) deletions doesn't match between otherwise
identical runs.
The following minimum working example seems to reproduce the problem;
uncomment the four lines in the input file to "fix" the problem:
** FILE mymol.txt **
3 atoms
Coords
1 0 0 -0.549
2 0 0 0.549
3 0 0 0
Types
1 1
2 1
3 2
** END FILE **
** FILE in.test **
units metal
atom_style bond
region myRegion block 0 10 0 10 0 10
create_box 2 myRegion
mass * 1
molecule nitrogens mymol.txt
pair_style hybrid lj/cut 12
pair_coeff 1 1 lj/cut 0.003140 3.32
pair_coeff 1 2 lj/cut 0 3.3
pair_coeff 2 2 lj/cut 0 3.3
#pair_style lj/cut 12
#pair_coeff 1 1 0.003140 3.32
#pair_coeff 1 2 0 3.3
#pair_coeff 2 2 0 3.3
fix 1 all gcmc 5000 40 500 0 1234 770 123 1 pressure 200 mol nitrogens
thermo_style custom step atoms press temp f_1[4] f_1[6] f_1[1] f_1[2]
run 100000