/*   []----------------------------------------[]
      |                Torsion.h               |
     []----------------------------------------[]
      |                                        |
      |   AUTHOR:    MFSomers 2005.            |
      |   USE:       Bond torsion 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(__GENERALTORSIONAL_INCLUDED__)

#define __GENERALTORSIONAL_INCLUDED__

#include <vector>

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

class   TorsionalInteraction;
typedef TorsionalInteraction *TorsionalInteractionPointer;

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

			      inline TorsionalInteraction( TorsionalInteraction& I ) : Interaction( I )
			      {
			      }
			      
			      virtual TorsionalInteractionPointer Clone()
		              {
		               return( new TorsionalInteraction( (*this) ) );
		              }
		              virtual TorsionalInteractionPointer Create( unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL )
		              {
		               return( new TorsionalInteraction( TheId, UsePeriodicBox ) );
		              }
			      
			      virtual double TorsionalPotential( double cosangle );
			      virtual double DerivativeOfTorsionalPotential( double cosangle );			      
			      
			      virtual double TorsionalPotential( Particle& P1, Particle& P2, Particle& P3, Particle& P4 );
			      virtual Vector TorsionalForce( Particle& P1, Particle& P2, Particle& P3, Particle& P4, int p );
			      
			      double TorsionalPotential( unsigned int ID1, unsigned int ID2, unsigned ID3, unsigned ID4 );
			      Vector TorsionalForce( unsigned int ID1, unsigned int ID2, unsigned ID3, unsigned ID4, int p );
			     
		              virtual double InteractionPotential( void );
			      virtual Vector InteractionForce( unsigned int ID );   
			     };

/* --------------------------------------------------------- */
/* Defines a periodic torsional interaction between particles */

class   PeriodicTorsionalInteraction;
typedef PeriodicTorsionalInteraction *PeriodicTorsionalInteractionPointer;

class PeriodicTorsionalInteraction : public TorsionalInteraction
                            {
		 	     public:
			     
			     inline PeriodicTorsionalInteraction( double TheFactor, double TheAngle, int TheN = 1, unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL ) : TorsionalInteraction( TheId, UsePeriodicBox )
			     {
			      InteractionFactor = TheFactor;
			      Angle = TheAngle;
			      N = ( TheN >= 1 ? TheN : 1 );
			      Type = APeriodicTorsionalInteraction;
			     };
			     inline PeriodicTorsionalInteraction( PeriodicTorsionalInteraction& I ) : TorsionalInteraction( I )
			     {
			      InteractionFactor = I.InteractionFactor;
			      Angle = I.Angle;
			      N = I.N;
			     }

			     virtual PeriodicTorsionalInteraction& operator=( PeriodicTorsionalInteraction& I )
			     {
			      if( &I == &(*this) ) return( (*this) );
			      TorsionalInteraction::operator=( I );
			      InteractionFactor = I.InteractionFactor;
			      Angle = I.Angle;
			      N = I.N;
			      return( (*this) );
			     } 			    
			     virtual PeriodicTorsionalInteractionPointer Clone()
		             {
		              return( new PeriodicTorsionalInteraction( (*this) ) );
		             }
		             virtual PeriodicTorsionalInteractionPointer Create( double TheFactor = 1.0, double TheAngle = 0.0,
			                                                 int TheN = 1, unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL )
		             {
		              return( new PeriodicTorsionalInteraction( TheFactor, TheAngle, TheN, TheId, UsePeriodicBox ) );
		             }			    
				    
			     virtual double TorsionalPotential( double cosangle );
			     virtual double DerivativeOfTorsionalPotential( double cosangle );		
			    
			     double InteractionFactor, Angle;        /* V(cosangle) = factor*[1-cos(N*{acos(cosangle)-Angle})] */
			     int    N;
			    };
			   
			     
/* ----------------------------------------------------------------------- */    

#endif