/*   []----------------------------------------[]
      |                 Morse.h                |
     []----------------------------------------[]
      |                                        |
      |   AUTHOR:    MFSomers 2005.            |
      |   USE:       Defines a Morse type      |
      |               interaction...           |
      |                                        |
     []----------------------------------------[]
*/

// Copyright (C) 2005 M.F. Somers, Theoretical Chemistry Department, Leiden University
//
// This is free software; you can redistribute it and/or modify it under the terms of
// the GNU Lesser General Public License as published by the Free Software Foundation.
//
// http://www.gnu.org/licenses/lgpl.txt

#if !defined(__MORSE_INCLUDED__)

#define __MORSE_INCLUDED__

#include "Global.h"
#include "Vector.h"
#include "Constants.h"
#include "ClassicalDynamics.h"
#include "PointPair.h"

/* --------------------------------------------------------- */
/* Defines a Morse pointpair interaction between particles */

class   MorseInteraction;
typedef MorseInteraction *MorseInteractionPointer;

class MorseInteraction : public PointPairInteraction
                         {
		 	  public:
			     
			  inline MorseInteraction( double TheD, double TheR, double TheAlfa, unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL ) : PointPairInteraction( TheId, UsePeriodicBox )
			  {
			   D = TheD;
			   R = TheR;
			   Alfa = TheAlfa;
			   Type = AMorseInteraction;
			  }
			  inline MorseInteraction( MorseInteraction& I ) : PointPairInteraction( I )
			  {
			   D = I.D;
			   R = I.R;
			   Alfa = I.Alfa;			   
			  }

          	          virtual MorseInteraction& operator=( MorseInteraction& I )
			  {
			   if( &I == &(*this) ) return( (*this) );
			   PointPairInteraction::operator=( I );
			   D = I.D;
			   R = I.R;
			   Alfa = I.Alfa;			   
			   return( (*this) );
			  } 			    
		          virtual MorseInteractionPointer Clone()
		          {
		           return( new MorseInteraction( (*this) ) );
		          }
		          virtual MorseInteractionPointer Create( double TheD = 1.0, double TheR = 1.0,
			                                          double TheAlfa = 1.0, unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL )
		          {
		           return( new MorseInteraction( TheD, TheR, TheAlfa, TheId, UsePeriodicBox ) );
		          }
				    
			  virtual double PointPairPotential( Particle& P1, Particle& P2 );
			  virtual Vector PointPairForce( Particle& P1, Particle& P2 );
			  
			  double D, R, Alfa;          /* V(r) = D * ( 1 - EXP(-Alfa(r-R)) )^2 - D */
			 };
			   
/* --------------------------------------------------------- */

#endif