FormFactorDWBA.cpp

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// ************************************************************************** //
//
//  BornAgain: simulate and fit scattering at grazing incidence
//
//! @file      Sample/Scattering/FormFactorDWBA.cpp
//! @brief     Implements class FormFactorDWBA.
//!
//! @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/Scattering/FormFactorDWBA.h"
#include "Sample/Material/WavevectorInfo.h"
#include "Sample/RT/ILayerRTCoefficients.h"
 
FormFactorDWBA::FormFactorDWBA(const IFormFactor& form_factor) : mP_form_factor(form_factor.clone())
{
    setName("FormFactorDWBA");
}
 
FormFactorDWBA::~FormFactorDWBA() = default;
 
FormFactorDWBA* FormFactorDWBA::clone() const
{
    FormFactorDWBA* result = new FormFactorDWBA(*mP_form_factor);
    std::unique_ptr<const ILayerRTCoefficients> p_in_coefs =
        mp_in_coeffs ? std::unique_ptr<const ILayerRTCoefficients>(mp_in_coeffs->clone()) : nullptr;
    std::unique_ptr<const ILayerRTCoefficients> p_out_coefs =
        mp_out_coeffs ? std::unique_ptr<const ILayerRTCoefficients>(mp_out_coeffs->clone())
                      : nullptr;
    result->setSpecularInfo(std::move(p_in_coefs), std::move(p_out_coefs));
    return result;
}
 
complex_t FormFactorDWBA::evaluate(const WavevectorInfo& wavevectors) const
{
    // Retrieve the two different incoming wavevectors in the layer
    cvector_t k_i_T = wavevectors.getKi();
    k_i_T.setZ(-mp_in_coeffs->getScalarKz());
    cvector_t k_i_R = k_i_T;
    k_i_R.setZ(-k_i_T.z());
 
    // Retrieve the two different outgoing wavevector bins in the layer
    cvector_t k_f_T = wavevectors.getKf();
    k_f_T.setZ(mp_out_coeffs->getScalarKz());
    cvector_t k_f_R = k_f_T;
    k_f_R.setZ(-k_f_T.z());
 
    // Construct the four different scattering contributions wavevector infos
    double wavelength = wavevectors.getWavelength();
    WavevectorInfo k_TT(k_i_T, k_f_T, wavelength);
    WavevectorInfo k_RT(k_i_R, k_f_T, wavelength);
    WavevectorInfo k_TR(k_i_T, k_f_R, wavelength);
    WavevectorInfo k_RR(k_i_R, k_f_R, wavelength);
 
    // Get the four R,T coefficients
    complex_t T_in = mp_in_coeffs->getScalarT();
    complex_t R_in = mp_in_coeffs->getScalarR();
    complex_t T_out = mp_out_coeffs->getScalarT();
    complex_t R_out = mp_out_coeffs->getScalarR();
 
    // The four different scattering contributions; S stands for scattering
    // off the particle, R for reflection off the layer interface
    complex_t term_S = T_in * mP_form_factor->evaluate(k_TT) * T_out;
    complex_t term_RS = R_in * mP_form_factor->evaluate(k_RT) * T_out;
    complex_t term_SR = T_in * mP_form_factor->evaluate(k_TR) * R_out;
    complex_t term_RSR = R_in * mP_form_factor->evaluate(k_RR) * R_out;
 
    return term_S + term_RS + term_SR + term_RSR;
}
 
double FormFactorDWBA::bottomZ(const IRotation& rotation) const
{
    return mP_form_factor->bottomZ(rotation);
}
 
double FormFactorDWBA::topZ(const IRotation& rotation) const
{
    return mP_form_factor->topZ(rotation);
}
 
void FormFactorDWBA::setSpecularInfo(std::unique_ptr<const ILayerRTCoefficients> p_in_coeffs,
                                     std::unique_ptr<const ILayerRTCoefficients> p_out_coeffs)
{
    mp_in_coeffs = std::move(p_in_coeffs);
    mp_out_coeffs = std::move(p_out_coeffs);
}