lijiext
/
lammps
mirror of https://github.com/lammps/lammps.git
1
0
Fork 1
Code Issues Packages Projects Releases Wiki Activity

add readme file to discuss various python pair style usage examples

This commit is contained in:
Axel Kohlmeyer 2017-05-18 00:31:54 -04:00
parent 09f3b687f7
commit 8d46aa6056
1 changed files with 41 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
examples/python/README.pair_python Normal file
View File

@ -0,0 +1,41 @@
This folder contains several LAMMPS input scripts and a python module
file py_pot.py to demonstrate the use of the pair style python.
in.pair_python_melt:
This is a version of the melt example using the python pair style. The first
part of the output should have identical energies, temperature and pressure
than the melt example. The following two sections then demonstrate how to
restart with pair style python from a restart file and a data file.
in.pair_python_hybrid:
This versions shows how to mix regular pair styles with a python pair style.
However, in this case both potentials are the same, so the energies and
pressure in the output should be identical to that of the previous example.
in.pair_python_spce:
This input shows a simulation of small bulk water system with the SPC/E
water potential. Since the python pair style does not support computing
coulomb contributions, pair style hybrid/overload is used to combine
the python style containing the Lennard-Jones part with the long-range coulomb.
Same as for the previous example, it also showcases restarting.
in.pair_python_table:
This input demonstrates the use of using the python pair style to build
a table file for use with pair style table. This will run much faster
than the python pair style. This example tabulates the melt example from
above. Note that tabulation is approximative, so the output will only
agree with the melt result to some degree.
in.pair_python_coulomb:
This is another tabulation example, this time for the SPC/E water example
with cutoff coulomb interactions.
Please note, that tabulating long-range coulomb has a systematic error in
forces and energies for all systems with bonds, angle and dihedrals.
In this case, this will only affect the energies, since the water molecules
are held rigid with fix shake. To enable long-range coulomb the coul/cut
style needs to be replaced with coul/long, a suitable kspace style added
and the pppm keyword added to the table pair style definition.
in.pair_python_long:
The final example shows how to combine long-range coulomb with tabulation
for only the short range interactions via pair style hybrid/overlay.