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// ************************************************************************************************
//
// BornAgain: simulate and fit reflection and scattering
//
//! @file Sample/Aggregate/Interference1DLattice.cpp
//! @brief Implements class Interference1DLattice.
//!
//! @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/Aggregate/Interference1DLattice.h"
#include "Base/Util/Assert.h"
#include "Sample/Correlation/Profiles1D.h"
#include "Sample/Correlation/Profiles2D.h"
#include <algorithm>
namespace {
// maximum value for qx*Lambdax
const int nmax = 20;
// minimum number of neighboring reciprocal lattice points to use
const int min_points = 4;
} // namespace
//! Constructor of interference function of one-dimensional lattice.
//! @param length: lattice constant in nanometers
//! @param xi: rotation of lattice with respect to x-axis in radians
Interference1DLattice::Interference1DLattice(double length, double xi)
: IInterference(0)
, m_length(length)
, m_xi(xi)
, m_na{0}
{
validateOrThrow();
}
Interference1DLattice::~Interference1DLattice() = default;
Interference1DLattice* Interference1DLattice::clone() const
{
auto* result = new Interference1DLattice(m_length, m_xi);
result->setPositionVariance(m_position_var);
result->m_na = m_na;
if (m_decay)
result->setDecayFunction(*m_decay);
return result;
}
//! Sets one-dimensional decay function.
//! @param decay: one-dimensional decay function in reciprocal space
void Interference1DLattice::setDecayFunction(const IProfile1D& decay)
{
m_decay.reset(decay.clone());
double decay_length = m_decay->decayLength();
double qa_max = m_length * nmax / decay_length / (2 * pi);
m_na = static_cast<int>(std::lround(std::abs(qa_max) + 0.5));
m_na = std::max(m_na, min_points);
}
std::vector<const INode*> Interference1DLattice::nodeChildren() const
{
return std::vector<const INode*>() << m_decay;
}
double Interference1DLattice::iff_without_dw(const R3& q) const
{
ASSERT(m_decay);
double result = 0.0;
double qxr = q.x();
double qyr = q.y();
double qx_frac;
double xi = m_xi;
double a = m_length;
double a_rec = (2 * pi) / a;
// rotate the q vector to xi angle
// so that qx_prime is along the a axis of lattice
double qx_prime = qxr * std::cos(xi) + qyr * std::sin(xi);
// calculate reciprocal vector fraction
int qa_int = static_cast<int>(qx_prime / a_rec);
qx_frac = qx_prime - qa_int * a_rec;
for (int i = -m_na; i < m_na + 1; ++i) {
double qx = qx_frac + i * a_rec;
result += m_decay->decayFT(qx);
}
return result / a;
}
std::string Interference1DLattice::validate() const
{
std::vector<std::string> errs;
requestGt0(errs, m_length, "latticeConstant");
if (!errs.empty())
return jointError(errs);
m_validated = true;
return "";
}
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