A few weeks ago I ran LAMMPS to calculate the pressure tensor. I had
expected that “pair_modify tail yes” would give more precise result than
“pair_modify shift yes”, but I turned out that when the former was used
the off-diagonal components of the pressure tensor would not converge
to zero, even for pure nve runs. While when the latter was employed,
there was no such problem. I am wondering if there is something wrong
with “tail” or it should be so?
Another thing is related to the OPLS dihedral coefficients. When we set
these parameters from “read_data”, we should provide the value for
“K”, while in the restart file, “K/2” is saved. When we use restart2data.cpp
to convert the binary into data file, what we get will still be “K/2”. As a result,
if we want to do another simulation from the data file, we have to multiply the
according parameters by a factor of 2. There won’t be any problem if we
restart from the restart files. What I suggest is to modify the restart2data.cpp
slightly to give “K” instead for OPLS dihedral potentials.
Thirdly, in both fix_ave_time.cpp and fix_ave_spatial.cpp, there is an instruction
“if (nvalid < update->ntimestep) error->all…”. This will frequently cause the
code to stop and is not desirable especially when one is using a queueing system
and finally get the chance to run. I would suggest to use
" if (nvalid < update->ntimestep) nvalid += nfreq" istead.
University of Western Ontario