/*   []----------------------------------------[]
      |             PointPair.cpp              |
     []----------------------------------------[]
      |                                        |
      |   AUTHOR:    MFSomers 2005.            |
      |   USE:       Point pair interaction    |
      |               functions...             |      
      |                                        |
     []----------------------------------------[]
*/

// 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

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

/* ----------------------------------------------------------------------- */

double PointPairInteraction::InteractionPotential( void )
{
 int             Pos1, Pos2;
 double          TotalPointPairPotential;
 ParticlePointer P1, P2;
 
 TotalPointPairPotential = 0.0;
 
 for( Pos1 = 0; Pos1 < Particles.size(); Pos1++ )
 {
  P1 = Particles[ Pos1 ];
  if( P1 == NULL )
    continue;  
    
  for( Pos2 = Pos1 + 1; Pos2 < Particles.size(); Pos2++ )
  {
   P2 = Particles[ Pos2 ];
   if( P2 == NULL )
    continue;
    
   TotalPointPairPotential += PointPairPotential( *P1, *P2 );  
  }
 }
  
 return( TotalPointPairPotential ); 
} 

/* ----------------------------------------------------------------------- */

Vector PointPairInteraction::InteractionForce( unsigned int ID )
{
 int             Pos1, Pos2;
 Vector          TotalPointPairVector;
 ParticlePointer P1, P2;
 
 TotalPointPairVector.X = 0.0;
 TotalPointPairVector.Y = 0.0; 
 TotalPointPairVector.Z = 0.0; 
 
 Pos1 = IsParticleIncluded( ID );
 
 if( Pos1 <= -1 )
  return( TotalPointPairVector ); 
  
 P1 = Particles[ Pos1 ]; 
 
 for( Pos2 = 0; Pos2 < Particles.size(); Pos2++ )
 {
  if( Pos1 == Pos2 )
   continue;
   
  P2 = Particles[ Pos2 ];
  
  if( P2 == NULL )
    continue;  
  
  TotalPointPairVector += PointPairForce( *P1, *P2 );  
 }
  
 return( TotalPointPairVector );
}

/* ----------------------------------------------------------------------- */

double PointPairInteraction::PointPairPotential( unsigned int ID1, unsigned int ID2 )
{
 int Pos1, Pos2;
 
 if( ID1 == ID2 )
  return( 0.0 );
 
 Pos1 = IsParticleIncluded( ID1 );
 if( Pos1 <= -1 ) 
  return( 0.0 );
  
 Pos2 = IsParticleIncluded( ID2 );
 if( Pos2 <= -1 )
  return( 0.0 );
  
 return( PointPairPotential( *(Particles[ Pos1 ]), *(Particles[ Pos2 ]) ) );  
}

/* ----------------------------------------------------------------------- */

Vector PointPairInteraction::PointPairForce( unsigned int ID1, unsigned int ID2 )
{
 int    Pos1, Pos2;
 Vector ZeroVector;
 
 ZeroVector.X = ZeroVector.Y = ZeroVector.Z = 0.0;
 
 if( ID1 == ID2 )
  return( ZeroVector );
 
 Pos1 = IsParticleIncluded( ID1 );
 if( Pos1 <= -1 ) 
  return( ZeroVector );
  
 Pos2 = IsParticleIncluded( ID2 );
 if( Pos2 <= -1 )
  return( ZeroVector );
  
 return( PointPairForce( *(Particles[ Pos1 ]), *(Particles[ Pos2 ]) ) );  
}

/* ----------------------------------------------------------------------- */

double PointPairInteraction::PointPairPotential( Particle& P1, Particle& P2 )
{
 return( 0.0 );
}

/* ----------------------------------------------------------------------- */

Vector PointPairInteraction::PointPairForce( Particle& P1, Particle& P2 )
{
 Vector ZeroVector;
 
 ZeroVector.X = ZeroVector.Y = ZeroVector.Z = 0.0;
 
 return( ZeroVector );
}

/* ----------------------------------------------------------------------- */