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# Contributors:
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#    Andrew Akerson
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This directory contains a Lennard-Jones Driver which reads a parameter file
containing the parameters for up to 139 species.  It supports shifted and
non-shifted energy behavior.  The driver is written in C++.  This Model Driver
expects one parameter file as decribed below.

The model driver implements the functional form:

       phi_{ij}(r) = 4 * epsilon_{ij} *
                     [ (sigma_{ij}/r)^12 - (sigma_{ij}/r)^6 ] + shift_{ij},

where i, j = 0, 1, 2, ..., N-1, and N is the number of supported species.


The format of the parameter file is as follows:

* Blank lines and lines beginning with the `#' character are ignored.

* Line 0 : N, shift
   - N         : integer number of distinct particle species
   - shift     : integer value: 0-for no shift; 1-for shifts.
                 All shift values are computed at run time
* Lines 1,2,...: species_i, species_j, cutoff, epsilon, sigma
   - species_i : A valid KIM API particle species string
   - species_j : A valid KIM API particle species string
   - cutoff    : double cutoff distance value (in Angstroms) for phi_{ij}(r)
   - epsilon   : double energy value (in eV) for  epsilon_{ij}
   - sigma     : double sigma distance value (in Angstroms) for sigma_{ij}


The parameter file must contain all "like-like" parameter sets (i.e., lines
where species_i and species_j are identical) for each species which occurs in
the file.  The model driver uses the Lorentz-Berthelot rules to generate any
"cross-interaction" parameter sets which are not provided.  The model driver
sets the `influcenceDistance' argument to max_{ij}(cutoff_{ij}).  The model
driver uses this same influenceDistance as its NeighborListCutoff value.