EllipsoidalCylinder.cpp

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//  ************************************************************************************************
//
//  BornAgain: simulate and fit reflection and scattering
//
//! @file      Sample/HardParticle/EllipsoidalCylinder.cpp
//! @brief     Implements class EllipsoidalCylinder.
//!
//! @homepage  http://www.bornagainproject.org
//! @license   GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2018
//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
//  ************************************************************************************************
 
#include "Sample/HardParticle/EllipsoidalCylinder.h"
#include "Base/Math/Bessel.h"
#include "Base/Math/Constants.h"
#include "Base/Math/Functions.h"
#include "Sample/Shapes/DoubleEllipse.h"
 
EllipsoidalCylinder::EllipsoidalCylinder(const std::vector<double> P)
    : IFormFactor(P)
    , m_radius_x(m_P[0])
    , m_radius_y(m_P[1])
    , m_height(m_P[2])
{
    checkNodeArgs();
    m_shape3D =
        std::make_unique<DoubleEllipseZ>(m_radius_x, m_radius_y, m_height, m_radius_x, m_radius_y);
}
 
EllipsoidalCylinder::EllipsoidalCylinder(double radius_x, double radius_y, double height)
    : EllipsoidalCylinder(std::vector<double>{radius_x, radius_y, height})
{
}
 
double EllipsoidalCylinder::radialExtension() const
{
    return (m_radius_x + m_radius_y) / 2.0;
}
 
complex_t EllipsoidalCylinder::formfactor_at_bottom(C3 q) const
{
    complex_t qxRa = q.x() * m_radius_x;
    complex_t qyRb = q.y() * m_radius_y;
    complex_t qzHdiv2 = m_height / 2 * q.z();
 
    complex_t Fz = exp_I(qzHdiv2) * Math::sinc(qzHdiv2);
    complex_t gamma = std::sqrt((qxRa) * (qxRa) + (qyRb) * (qyRb));
    complex_t J1_gamma_div_gamma = Math::Bessel::J1c(gamma);
 
    return M_TWOPI * m_radius_x * m_radius_y * m_height * Fz * J1_gamma_div_gamma;
}