charmmTorsion.h

// -*- Mode: C++; tab-width: 2; -*-
// vi: set ts=2:
//
// $Id: charmmTorsion.h,v 1.20.18.1 2007/03/25 21:23:49 oliver Exp $
//

// Molecular Mechanics: CHARMM force field, proper torsion component

#ifndef BALL_MOLMEC_CHARMM_CHARMMTORSION_H
#define BALL_MOLMEC_CHARMM_CHARMMTORSION_H

#ifndef BALL_COMMON_H
# include <BALL/common.h>
#endif

#ifndef BALL_MOLMEC_PARAMETER_COSINETORSION_H
# include <BALL/MOLMEC/PARAMETER/cosineTorsion.h>
#endif

#ifndef BALL_MOLMEC_PARAMETER_RESIDUETORSIONS_H
# include <BALL/MOLMEC/PARAMETER/residueTorsions.h>
#endif

#ifndef BALL_MOLMEC_COMMON_FORCEFIELDCOMPONENT_H
# include <BALL/MOLMEC/COMMON/forceFieldComponent.h>
#endif

#ifndef BALL_MOLMEC_COMMON_FORCEFIELD_H
# include <BALL/MOLMEC/COMMON/forceField.h>
#endif

namespace BALL 
{
  class BALL_EXPORT CharmmTorsion 
    : public ForceFieldComponent
  {
    public:

    #define CHARMM_TORSIONS_ENABLED "enable Torsions"


    struct SingleCharmmTorsion 
    {
      Atom* atom1;
      Atom* atom2;
      Atom* atom3;
      Atom* atom4;

      float   V;
      unsigned char f;
      float   phase;

      SingleCharmmTorsion()
        : atom1(0),
          atom2(0),
          atom3(0),
          atom4(0),
          V(0),
          f(0),
          phase(0)
      {
      }

      SingleCharmmTorsion(CosineTorsion::SingleData& t)
      {
        atom1 = t.atom1;
        atom2 = t.atom2;
        atom3 = t.atom3;
        atom4 = t.atom4;

        V = t.values.V / t.values.n;
        f = (unsigned char)t.values.f;

        // convert phase from degrees to radiant
        phase = (float)(BALL::Constants::PI / 180.0) * t.values.phase;
      }
    };



    BALL_CREATE(CharmmTorsion)

    
    CharmmTorsion();

    CharmmTorsion(ForceField& force_field);

    CharmmTorsion(const CharmmTorsion& charmm_stretch);

    virtual ~CharmmTorsion();



    virtual bool setup()
      throw(Exception::TooManyErrors);



    virtual double updateEnergy();

    virtual void updateForces();


    private:

    /*_ @name Private Attributes  
    */
    //_@{

    /*_ Vector containing the parameters for each torsion.
    */
    vector<SingleCharmmTorsion>   torsion_;

    /*_ Contents of the [Torsions] section of the parameter file.
    */
    CosineTorsion                 torsion_parameters_;    

    /*_ Contents of the [ResidueTorsions] section of the parameter file.
    */
    ResidueTorsions               residue_torsions_;

    /*_ true, if the torsions are read from the ResidueTorsions section.
    */
    bool use_residue_torsion_list_;

    //_@}
   
  };
} // namespace BALL 

#endif // BALL_MOLMEC_CHARMM_CHARMMTORSION_H

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