first few pieces of pair style python

src/PYTHON/pair_python.h

@@ -0,0 +1,74 @@
+/* -*- c++ -*- ----------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+
+   Pair zero is a dummy pair interaction useful for requiring a
+   force cutoff distance in the absense of pair-interactions or
+   with hybrid/overlay if a larger force cutoff distance is required.
+
+   This can be used in conjunction with bond/create to create bonds
+   that are longer than the cutoff of a given force field, or to
+   calculate radial distribution functions for models without
+   pair interactions.
+
+------------------------------------------------------------------------- */
+
+#ifdef PAIR_CLASS
+
+PairStyle(python,PairPython)
+
+#else
+
+#ifndef LMP_PAIR_PYTHON_H
+#define LMP_PAIR_PYTHON_H
+
+#include "pair.h"
+
+namespace LAMMPS_NS {
+
+class PairPython : public Pair {
+ public:
+  PairPython(class LAMMPS *);
+  virtual ~PairPython();
+  virtual void compute(int, int);
+  void settings(int, char **);
+  void coeff(int, char **);
+  double init_one(int, int);
+
+ protected:
+  double cut_global;
+
+  virtual void allocate();
+};
+
+}
+
+#endif
+#endif
+
+/* ERROR/WARNING messages:
+
+E: Illegal ... command
+
+Self-explanatory.  Check the input script syntax and compare to the
+documentation for the command.  You can use -echo screen as a
+command-line option when running LAMMPS to see the offending line.
+
+E: Incorrect args for pair coefficients
+
+Self-explanatory.  Check the input script or data file.
+
+E: Pair cutoff < Respa interior cutoff
+
+One or more pairwise cutoffs are too short to use with the specified
+rRESPA cutoffs.
+
+*/