[lammps-users] A querry regarding LAMMPS

Dear Sir/Madam,
                I want to perform Grand Canonical Molecular Dynamics
simulations.Do LAMMPS have this GCMD simulation facility.
Thanks in advance.
                                                         Yours sincerely,

With regards

no - but you could write a fix to add/delete atoms for the GC part
if you wished - however general GC is a non-trivial matter
with many algorithms and possibilities.


Dear all,

Sorry to bother you, but I'm really stuck with the following error:

"Virial was not tallied on needed timestep"

when I'm trying to print pxy on every timestep, using a nve integrator:

fix 1 all nve
variable pxy equal pxy
fix 2 all print 1 "${pxy}" file print.viscosity screen no

The problem does not appear when using a npt integrator.

I looked at the error section of the documentation:

"You are using a thermo keyword that requires potentials to have tallied the
virial, but they didn't on this timestep. See the variable doc page for ideas
on how to make this work."

but could not find on the variable doc page the answer to this problem...

I tried to define my own compute pressure and temp, but got the same error

Do you have an idea on how this problem can be solved ?

Please find enclosed the complete imput script for information. I'm using

Best regards,
Laurent Joly

in.viscosity (829 Bytes)

This was a bug with fix print. I just posted a patch.