c CCLRC
Section 4.2
4.2.1.3
Note on the DL POLY 3 Interpolation Scheme
In DL POLY 3 the some short-range-like contributions (Van der Waals, Sutton Chen, real space
Ewald summation) to energy and force are evaluated by interpolation of tables constructed at
the beginning of execution. The DL POLY 3 interpolation scheme is based on a 3-point linear
interpolation in r.
The number of grid points (mxgrid) required for interpolation in r to give good energy conservation
in a simulation is:
mxgrid = Max(1000, Int(r
cut
/0.01 + 0.5) + 4) ,
where r
cut
is the main cutoff beyond which the contributions from the short-range-like interactions
are negligible.
4.2.2
Running DL POLY 3
To run the DL POLY 3 executable (DLPOLY.Y) you will initially require three, possibly four,
input data files, which you must create in the execute sub-directory, (or whichever sub-directory
you keep the executable program). The first of these is the CONTROL file (Section
indicates to DL POLY 3 what kind of simulation you want to run, how much data you want to
gather and for how long you want the job to run. The second file you need is the CONFIG file
(Section
). This contains the atom positions and, depending on how the file was created (e.g.
whether this is a configuration created from `scratch' or the end point of another run), the velocities
and forces also. The third file required is the FIELD file (Section
), which specifies the nature
of the intermolecular interactions, the molecular topology and the atomic properties, such as charge
and mass. Sometimes you will require a fourth file: TABLE (Section
potential and force arrays for functional forms not available within DL POLY 3 (usually because
they are too complex e.g. spline potentials).
Examples of input files are found in the data sub-directory, which can be copied into the execute
subdirectory using the select macro found in the execute sub-directory.
A successful run of DL POLY 3 will generate several data files, which appear in the execute sub-
directory. The most obvious one is the file OUTPUT (Section
), which provides an effective
summary of the job run: the input information; starting configuration; instantaneous and rolling-
averaged thermodynamic data; final configurations; radial distribution functions (RDFs); and job
timing data. The OUTPUT file is human readable. Also present will be the restart files REVIVE
(Section
). REVIVE contains the accumulated data for a number
of thermodynamic quantities and RDFs, and is intended to be used as the input file for a following
run. It is not human readable. The REVCON file contains the restart configuration i.e. the final
positions, velocities and forces of the atoms when the run ended and is human readable. The
STATIS file (Section
) contains a catalogue of instantaneous values of thermodynamic and
other variables, in a form suitable for temporal or statistical analysis. Finally, the HISTORY file
(Section
) provides a time ordered sequence of configurations to facilitate further analysis of
the atomic motions. By default this file is formatted (human readable) but with little effort from
the user it can be generated unformatted. You may move these output files back into the data
sub-directory using the store macro found in the execute sub-directory.
Lastly, DL POLY 3 may also create the files RDFDAT and ZDNDAT, containing the RDF and
Z-density data respectively. They are both human readable files.
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