ScreeningFunction.h

Go to the documentation of this file.

// n2p2 - A neural network potential package
// Copyright (C) 2021 Andreas Singraber
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
#ifndef SCREENINGFUNCTION_H
#define SCREENINGFUNCTION_H
 
#include "CoreFunction.h"
 
namespace nnp
{

class ScreeningFunction
{
public:
    ScreeningFunction();
    void                     setCoreFunction(CoreFunction::Type const type);
    void                     setCoreFunction(std::string const type);
    void                     setInnerOuter(double inner, double outer);
    CoreFunction::Type       getCoreFunctionType() const;
    double                   getInner() const;
    double                   getOuter() const;
    void                     changeLengthUnits(double const conv);
    double                   f(double r) const;
    double                   df(double r) const;
    void                     fdf(double r, double& fr, double& dfr) const;
    std::vector<std::string> info() const;
 
 
private:
    double       inner;
    double       outer;
    double       scale;
    CoreFunction core;
 
};

// Inlined function definitions //
 
inline void ScreeningFunction::setCoreFunction(CoreFunction::Type const type)
{
    core.setType(type);
 
    return;
}
 
inline void ScreeningFunction::setCoreFunction(std::string const typeString)
{
    core.setType(typeString);
 
    return;
}
 
inline CoreFunction::Type ScreeningFunction::getCoreFunctionType() const
{
    return core.getType();
}
 
inline double ScreeningFunction::getInner() const { return inner; }
inline double ScreeningFunction::getOuter() const { return outer; }
 
inline double ScreeningFunction::f(double r) const
{
    if      (r >= outer) return 1.0;
    else if (r <= inner) return 0.0;
    else return 1.0 - core.f((r - inner) * scale);
}
 
inline double ScreeningFunction::df(double r) const
{
    if (r >= outer || r <= inner) return 0.0;
    else return -scale * core.df((r - inner) * scale);
}
 
inline void ScreeningFunction::fdf(double r, double& fr, double& dfr) const
{
    if (r >= outer)
    {
        fr = 1.0;
        dfr = 0.0;
    }
    else if (r <= inner)
    {
        fr = 0.0;
        dfr = 0.0;
    }
    else
    {
        core.fdf((r - inner) * scale, fr, dfr);
        fr = 1.0 - fr;
        dfr = -scale * dfr;
    }
 
    return;
}
 
}
 
#endif