fix viscosity?

Dear users,

I am trying to use the Muller-Plathe viscosity example on my molecule in LAMMPS version Feb. 16, 2016. The “fix 4 all viscosity 100 x y 20” line is giving me issues (input and example files in attachment). Does anyone know why?

log file with viscosity fix:

#viscosity

turn on Muller-Plathe driving force and equilibrate some more

compute chunk all chunk/atom molecule

fix 4 all viscosity 100 x y 20
ERROR: Unknown fix style (…/modify.cpp:793)

log file with viscosity commented out:

#viscosity

turn on Muller-Plathe driving force and equilibrate some more

compute chunk all chunk/atom molecule

#fix 4 all viscosity 100 x y 20

fix 5 all ave/chunk 20 50 1000 chunk vx file profile.mp.2d

#fix 5 all ave/spatial 20 50 1000 y center 0.05 vx # units reduced file >profile.mp.2d

equilibration run

variable dVx equal f_5[11][3]-f_5[1][3]

thermo 1000
thermo_style custom step temp epair etotal press f_4 v_dVx
ERROR: Could not find thermo custom fix ID (…/thermo.cpp:887)

Thanks in advance,
Tyler

in.mp.2d (1.62 KB)

input_lammps-visc-01 (2.37 KB)