lattice_change_cg.h

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#ifndef LATTICE_CHANGE_CG_H
#define LATTICE_CHANGE_CG_H
 
#include "source_base/matrix.h"
#include "source_cell/unitcell.h"
class Lattice_Change_CG
{
 
  public:
    Lattice_Change_CG();
    ~Lattice_Change_CG();
 
    void allocate(void);
    void start(UnitCell &ucell, const ModuleBase::matrix &stress_in, const double &etot);
 
  private:
    double *lat0;
    double *grad0;
    double *cg_grad0;
    double *move0;
    double e0=0.0;
 
    // setup gradients.
    void setup_cg_grad(double *grad,
                       const double *grad0,
                       double *cg_grad,
                       const double *cg_grad0,
                       const int &ncggrad,
                       int &flag);
 
    void setup_move(double *move, double *cg_gradn, const double &trust_radius);
 
    void Brent(double &fa, double &fb, double &fc, double &xa, double &xb, double &xc, double &best_x, double &xpt);
 
    void f_cal(const double *g0, const double *g1, const int &dim, double &f_value);
 
    void third_order(const double &e0,
                     const double &e1,
                     const double &fa,
                     const double &fb,
                     const double x,
                     double &best_x);
};
 
#endif