[lammps-users] shifted force Lennard-Jones pair style

Dear all,

I wrote a shifted force Lennard-Jones pair style for lammps:

http://link.aip.org/link/doi/10.1063/1.3558787 and references therin:

S. D. Stoddard and J. Ford, Phys. Rev. A 8, 1504 (1973);
J. J. Nicolas, K. E. Gubbins, W. B. Street, and D. J. Tildesley, Mol.
Phys. 37, 1429 (1979);
J. G. Powles, W. A. B. Evans, and N. Quirke, ibid. 46, 1347 (1982).
D. Wolf, P. Keblinski, S. R. Phillpot, and J. Eggebrecht, J. Chem.
Phys. 110, 8254 (1999);
D. Zahn, B. Schilling, and S. M. Kast, J. Phys. Chem. B 106, 10725 (2002);
C. J. Fennell and J. D. Gezelter, J. Chem. Phys. 124, 234104 (2006).

I started from pair_lj_cut but simplified it in the spirit of
pair_lj_smooth. In particular this pair style can only be used via the
pair keyword of the run_style respa command.

While doing this, I noticed that "init_list" and "extract" class
methods are not mentioned in the "modifying lammps" section of the
manual:

http://lammps.sandia.gov/doc/Section_modify.html#pair

I also noticed that there is no check for the positivity of the
cut-offs (cut_global and cut_one) in pair_lj_cut. Even if I don't see
why someone would do that, it is possible to specify negative cut-offs
with pair_style lj/cut without lammps issuing an error.

Enclosed are the source files. If you're interested to include it in
lammps, I can write the related doc page, so just tell me.

Best,
Laurent

pair_lj_sf.cpp (10.6 KB)

pair_lj_sf.h (1.37 KB)

Enclosed are the source files. If you're interested to include it in
lammps, I can write the related doc page, so just tell me.

yes - please write a doc page (as a doc/*.txt file) and we'll
include it. The equation(s) should be in the doc/Eqs/*,tex form
of simple LaTeX files.

I also noticed that there is no check for the positivity of the
cut-offs (cut_global and cut_one) in pair_lj_cut. Even if I don't see
why someone would do that, it is possible to specify negative cut-offs
with pair_style lj/cut without lammps issuing an error.

There are likely many places where such a check is not done. If
the user specifies a negative cutoff, he/she needs more help
than an error message.

Steve

Here are the doc files. I hope this comes good in html. What tool do
you use to convert from txt+tex to html?

Best,
Laurent

pair_lj_sf.txt (2.42 KB)

pair_lj_sf.tex (581 Bytes)