/*   []----------------------------------------[]
      |                Bending.h               |
     []----------------------------------------[]
      |                                        |
      |   AUTHOR:    MFSomers 2005.            |
      |   USE:       Bond bending interaction  |
      |               definitions...           |      
      |                                        |
     []----------------------------------------[]
*/

// 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(__GENERALBENDING_INCLUDED__)

#define __GENERALBENDING_INCLUDED__

#include <vector>

#include "Global.h"
#include "Vector.h"
#include "Constants.h"
#include "ClassicalDynamics.h"
       
/* ----------------------------------------------------------------------- */       
/* Definition of a bond bending interaction */

class   BendingInteraction;
typedef BendingInteraction *BendingInteractionPointer;

class BendingInteraction : public Interaction
                             {
		              public:
			     
			      inline BendingInteraction( unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL ) : Interaction( TheId, UsePeriodicBox )
			      {
			       Type = AGeneralBendingInteraction;
			      };

			      inline BendingInteraction( BendingInteraction& I ) : Interaction( I )
			      {
			      }
			      
			      virtual BendingInteractionPointer Clone()
		              {
		               return( new BendingInteraction( (*this) ) );
		              }
		              virtual BendingInteractionPointer Create( unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL )
		              {
		               return( new BendingInteraction( TheId, UsePeriodicBox ) );
		              }
			      
			      virtual double BendingPotential( double cosangle );
			      virtual double DerivativeOfBendingPotential( double cosangle );
			      
			      virtual double BendingPotential( Particle& P1, Particle& P2, Particle& P3 );
			      virtual Vector BendingForce( Particle& P1, Particle& P2, Particle& P3, int p );
			      
			      double BendingPotential( unsigned int ID1, unsigned int ID2, unsigned ID3 );
			      Vector BendingForce( unsigned int ID1, unsigned int ID2, unsigned ID3, int p );
			     
		              virtual double InteractionPotential( void );
			      virtual Vector InteractionForce( unsigned int ID );   
			     };
			     
/* --------------------------------------------------------- */
/* Defines a harmonic bond bending interaction between particles */

class   HarmonicBendingInteraction;
typedef HarmonicBendingInteraction *HarmonicBendingInteractionPointer;

class HarmonicBendingInteraction : public BendingInteraction
                            {
		 	     public:
			     
			     inline HarmonicBendingInteraction( double TheFactor, double TheAngle, unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL ) : BendingInteraction( TheId, UsePeriodicBox )
			     {
			      InteractionFactor = TheFactor;
			      CosAngle = cos( TheAngle );
			      Type = AHarmonicBendingInteraction;
			     };
			     inline HarmonicBendingInteraction( HarmonicBendingInteraction& I ) : BendingInteraction( I )
			     {
			      InteractionFactor = I.InteractionFactor;
			      CosAngle = I.CosAngle;
			     }

			     virtual HarmonicBendingInteraction& operator=( HarmonicBendingInteraction& I )
			     {
			      if( &I == &(*this) ) return( (*this) );
			      BendingInteraction::operator=( I );
			      InteractionFactor = I.InteractionFactor;
			      CosAngle = I.CosAngle;
			      return( (*this) );
			     } 			    
			     virtual HarmonicBendingInteractionPointer Clone()
		             {
		              return( new HarmonicBendingInteraction( (*this) ) );
		             }
		             virtual HarmonicBendingInteractionPointer Create( double TheFactor = 1.0, double TheAngle = 0.0, unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL )
		             {
		              return( new HarmonicBendingInteraction( TheFactor, acos( TheAngle ), TheId, UsePeriodicBox ) );
		             }			    
				    
			     virtual double BendingPotential( double cosangle );
			     virtual double DerivativeOfBendingPotential( double cosangle );
			    
			     double InteractionFactor, CosAngle;        /* V(cosangle) = 0.5 * TheFactor * (cosangle-CosAngle)^2 */
			    };
			   
/* ----------------------------------------------------------------------- */    

#endif