LJ.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).
 */
 
#ifndef NONBONDED_LJ_HPP
#define NONBONDED_LJ_HPP
 
#include "brains/ForceField.hpp"
#include "math/Vector3.hpp"
#include "nonbonded/NonBondedInteraction.hpp"
 
using namespace std;
namespace OpenMD {
 
  struct LJInteractionData {
    RealType sigma;
    RealType epsilon;
    RealType sigmai;
    bool explicitlySet;
  };
 
  class LJ : public VanDerWaalsInteraction {
  public:
    LJ();
    void setForceField(ForceField* ff) { forceField_ = ff; };
    void setSimulatedAtomTypes(AtomTypeSet& simtypes) {
      simTypes_ = simtypes;
      initialize();
    };
    void addType(AtomType* atomType);
    void addExplicitInteraction(AtomType* atype1, AtomType* atype2,
                                RealType sigma, RealType epsilon);
    virtual void calcForce(InteractionData& idat);
    virtual string getName() { return name_; }
    virtual int getHash() { return LJ_INTERACTION; }
    virtual RealType getSuggestedCutoffRadius(
        pair<AtomType*, AtomType*> atypes);
 
  private:
    void initialize();
    RealType getSigma(AtomType* atomType1, AtomType* atomType2);
    RealType getEpsilon(AtomType* atomType1, AtomType* atomType2);
 
    void getLJfunc(const RealType r, RealType& pot, RealType& deriv);
 
    bool initialized_;
 
    set<int> LJtypes;   /**< The set of AtomType idents that are LJ types */
    vector<int> LJtids; /**< The mapping from AtomType ident -> LJ type ident */
    vector<vector<LJInteractionData>>
        MixingMap; /**< The mixing parameters between two LJ types */
    int nLJ_;
    ForceField* forceField_;
    AtomTypeSet simTypes_;
    string name_;
  };
}  // namespace OpenMD
 
#endif