/* -*- 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.
------------------------------------------------------------------------- */

/* ----------------------------------------------------------------------
    Contributing authors: 
             Rodrigo Freitas (UC Berkeley) - rodrigof@berkeley.edu
             Mark Asta (UC Berkeley) - mdasta@berkeley.edu
             Maurice de Koning (Unicamp/Brazil) - dekoning@ifi.unicamp.br
------------------------------------------------------------------------- */

#ifdef FIX_CLASS

FixStyle(ti/spring,FixTISpring)

#else

#ifndef LMP_FIX_TI_SPRING_H
#define LMP_FIX_TI_SPRING_H

#include "fix.h"

namespace LAMMPS_NS {

class FixTISpring : public Fix {
 public:
  FixTISpring(class LAMMPS *, int, char **);
  ~FixTISpring();
  int    setmask();
  void   init();
  void   setup(int);
  void   min_setup(int);
  void   post_force(int);
  void   post_force_respa(int, int, int);
  void   min_post_force(int);
  void   initial_integrate(int);
  double compute_scalar();
  double compute_vector(int);
  
  double memory_usage();
  void   grow_arrays(int);
  void   copy_arrays(int, int, int);
  int    pack_exchange(int, double *);
  int    unpack_exchange(int, double *);
  int    pack_restart(int, double *);
  void   unpack_restart(int, int);
  int    size_restart(int);
  int    maxsize_restart();

 private:
  double switch_func(double);  // Switching function.
  double dswitch_func(double); // Switching function derivative.

  double k;           // Spring constant.
  double espring;     // Springs energies.
  double **xoriginal; // Original coords of atoms.
  double lambda;      // Coupling parameter.
  double dlambda;     // Lambda variation with t.
  double linfo[2];    // Current lambda status.
  bigint t_switch;    // Total switching steps.
  bigint t_equil;     // Equilibration time.
  bigint t0;          // Initial time.
  int    sf;          // Switching function option.
  int    nlevels_respa;
};

}

#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: Illegal fix ti/spring switching function

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.

*/
