CubicBendType.hpp

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 * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your
 * research, please cite the appropriate papers when you publish your
 * work.  Good starting points are:
 *
 * [1] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).
 * [2] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).
 * [3] Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).
 * [4] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
 * [5] Kuang & Gezelter, Mol. Phys., 110, 691-701 (2012).
 * [6] Lamichhane, Gezelter & Newman, J. Chem. Phys. 141, 134109 (2014).
 * [7] Lamichhane, Newman & Gezelter, J. Chem. Phys. 141, 134110 (2014).
 * [8] Bhattarai, Newman & Gezelter, Phys. Rev. B 99, 094106 (2019).
 */
 
/**
 * @file BendType.hpp
 * @author    tlin
 * @date  11/01/2004
 * @version 1.0
 */
 
#ifndef TYPES_CUBICBENDTYPE_HPP
#define TYPES_CUBICBENDTYPE_HPP
 
#include "types/BendType.hpp"
 
namespace OpenMD {
  /**
   * @class CubicBendType
   * @todo document
   */
  class CubicBendType : public BendType {
  public:
    CubicBendType(RealType theta, RealType k3, RealType k2, RealType k1,
                  RealType k0) :
        BendType(theta),
        k3_(k3), k2_(k2), k1_(k1), k0_(k0) {}
 
    void setForceConstant(RealType k3, RealType k2, RealType k1, RealType k0) {
      k3_ = k3;
      k2_ = k2;
      k1_ = k1;
      k0_ = k0;
    }
 
    void getForceConstant(RealType& k3, RealType& k2, RealType& k1,
                          RealType& k0) {
      k3 = k3_;
      k2 = k2_;
      k1 = k1_;
      k0 = k0_;
    }
 
    virtual void calcForce(RealType theta, RealType& V, RealType& dVdTheta) {
      RealType delta  = theta - theta0_;
      RealType delta2 = delta * delta;
      RealType delta3 = delta2 * delta;
 
      V        = k0_ + k1_ * delta + k2_ * delta2 + k3_ * delta3;
      dVdTheta = k1_ + 2.0 * k2_ * delta + 3.0 * k3_ * delta2;
    }
 
  private:
    RealType k3_;
    RealType k2_;
    RealType k1_;
    RealType k0_;
  };
}  // namespace OpenMD
 
#endif  // TYPES_CUBICBENDTYPE_HPP