Using fix gcmc without molecule insertion

Hello All,

I have the following script which I am trying to implement. I keep on getting an error about invalid atom type in ‘fix gcmc’ command. I want to just implement MC moves and not perform any molecule insertions/deletions. Somehow, i’m unable to debug the script. I don’t require the mol option to be turned on. Can anyone help me out with this?


units si

dimension 3

boundary p p p

atom_style full



group grp type 1 2

neighbor 2.0e-10 bin

neigh_modify delay 0 every 1 check yes one 7000

velocity ch create 500 36990 dist gaussian

fix 4 grp nvt temp 500 500 1.0e-13

fix 5 grp gcmc 100 0 100 1 54341 500.0 -2.1 0.5 full_energy

thermo 20

compute vir_p all pressure NULL virial

variable v_press1 equal c_vir_p[1]

variable v_press2 equal c_vir_p[2]

variable v_press3 equal c_vir_p[3]

variable v_press4 equal c_vir_p[4]

variable v_press5 equal c_vir_p[5]

variable v_press6 equal c_vir_p[6]

variable vir_press equal (v_v_press1+v_v_press2+v_v_press3+v_v_press4+v_v_press5+v_v_press6)

thermo_style custom step temp press v_vir_press vol density pxx pyy pzz pxy pxz pyz pe ke etotal epair ebond eangle edihed

thermo_modify lost warn norm no

timestep 1.0e-15

run 20000


Are type 1 and 2 part of a molecule ? …
If that so the manual says that fix gcmc gives a warning of error (I don’t remember) about moving on individual atoms that are part of a molecule

why don’t you attached the xyz file with the force field so someone can reproduce the error