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#ifndef CBPOTENTIAL_H
#define CBPOTENTIAL_H
namespace ATC
{
//! Enumerated list of interaction types
enum Interaction{PAIRWISE=1, EAM=2, THREE_BDY=4, ANGLE_BND=8};
//! Booleans that enable types of terms the potential uses.
struct Interactions {
//! Enables up to 3 interaction types. (order independant)
Interactions(int a=0, int b=0, int c=0);
bool pairwise; //!< Pairwise interaction terms exist.
bool embedding; //!< Embedding interaction terms (EAM) exist.
bool three_body; //!< Three-body interaction terms exist.
bool angle_bending; //!< Angle bending interaction terms exist.
};
//! Compute bond angle jik from the squared length of vectors ij,ik,kj.
double calculate_theta(double ij2, double ik2, double jk2);
/**
* @class CbPotential
* @brief Base class for computing Cauchy-Born quantities for an interatomic potential material
* (assume all terms return 0)
*/
class CbPotential
{
protected:
//! CbPotential base constructor:
//! Initializes which terms are included in energy computation.
//@param potential_terms Switches for atomic interaction terms.
CbPotential(Interactions interaction_terms) : terms(interaction_terms) {}
public:
virtual ~CbPotential() {}
const Interactions terms; //!< switches for types of potential terms.
//! Returns the minimum distance that all interactions get neglected.
virtual double cutoff_radius() const=0;
//! @name Pairwise interaction term and derivatives.
//@{
virtual double phi (const double &r) const { return 0.0; }
virtual double phi_r (const double &r) const;
virtual double phi_rr (const double &r) const;
virtual double phi_rrr(const double &r) const;
//@}
//! @name Embedding terms. Electron cloud density and embedding functions
//@{
virtual double rho (const double &r) const { return 0.0; }
virtual double rho_r (const double &r) const;
virtual double rho_rr(const double &r) const;
virtual double rho_rrr(const double &r) const;
virtual double F (const double &p) const { return 0.0; }
virtual double F_p (const double &p) const;
virtual double F_pp(const double &p) const;
virtual double F_ppp(const double &p) const;
//@}
//! @name Three-body terms and derivatives
//@{
virtual double phi3 (const double &q) const {return 0.0; }
virtual double phi3_q (const double &q) const;
virtual double phi3_qq(const double &q) const;
//@}
};
}
#endif