TorsionConstraint.h 3.14 KB
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////////////////////////////////////////////////////////////////////////////////
//
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// Copyright (c) 2008 The Regents of the University of California
//
// This file is part of Qbox
//
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// Qbox is distributed under the terms of the GNU General Public License
// as published by the Free Software Foundation, either version 2 of
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// the License, or (at your option) any later version.
// See the file COPYING in the root directory of this distribution
// or <http://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////////////
//
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// TorsionConstraint.h
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//
////////////////////////////////////////////////////////////////////////////////

#ifndef TORSIONCONSTRAINT_H
#define TORSIONCONSTRAINT_H

#include "Constraint.h"
#include "D3vector.h"
#include <cassert>
class AtomSet;

class TorsionConstraint : public Constraint
{
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  std::string name1_, name2_, name3_, name4_;
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  int    ia1_, ia2_, ia3_, ia4_, is1_, is2_, is3_, is4_;
  double m1_, m2_, m3_, m4_, m1_inv_, m2_inv_, m3_inv_, m4_inv_;
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  double angle_, velocity_, force_, weight_, tol_, sin_angle_, cos_angle_;
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  double sigma(D3vector a, D3vector b,
               D3vector c, D3vector d) const;
  void grad_sigma(const D3vector &r1, const D3vector &r2,
                    const D3vector &r3, const D3vector &r4,
                    D3vector &g1, D3vector &g2,D3vector &g3,D3vector &g4) const;
  double torsion_angle(D3vector a, D3vector b,
                       D3vector c, D3vector d) const;
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  public:
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  TorsionConstraint(std::string name, std::string name1, std::string name2,
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                    std::string name3, std::string name4,
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                    double angle, double velocity, double tolerance):
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  name1_(name1), name2_(name2), name3_(name3), name4_(name4),
  velocity_(velocity),
  tol_(tolerance), m1_(0.0), m2_(0.0), m3_(0.0), m4_(0.0)
  {
    set_value(angle);
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    name_ = name;
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    names_.resize(4);
    names_[0] = name1_;
    names_[1] = name2_;
    names_[2] = name3_;
    names_[3] = name4_;
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    force_ = 0.0;
    weight_ = 1.0;
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  }
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  ~TorsionConstraint(void) {}
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  std::string type(void) const { return "torsion"; }
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  double value(void) const { return angle_; }
  double velocity(void) const { return velocity_; }
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  double force(void) const { return force_; }
  double weight(void) const { return weight_; }
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  double tolerance(void) const { return tol_; }
  void set_value(double value)
  {
    angle_ = value;
    if ( angle_ < -180.0 ) angle_ = 180.0;
    if ( angle_ >  180.0 ) angle_ = 180.0;
    sin_angle_ = sin((M_PI/180.0)*angle_);
    cos_angle_ = cos((M_PI/180.0)*angle_);
  }
  void set_velocity(double velocity)
  {
    velocity_ = velocity;
  }
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  void setup(const AtomSet& atoms);
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  int dofs(void) const { return 1; }
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  void update(double dt);
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  bool enforce_r(const std::vector<std::vector<double> > &r0,
                 std::vector<std::vector<double> > &rp) const;
  bool enforce_v(const std::vector<std::vector<double> > &r0,
                 std::vector<std::vector<double> > &v0) const;
  void compute_force(const std::vector<std::vector<double> > &r0,
                     const std::vector<std::vector<double> > &f);
  std::ostream& print( std::ostream& os );
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};
#endif