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// ************************************************************************************************
//
// libformfactor: efficient and accurate computation of scattering form factors
//
//! @file demo/octahedron.cpp
//! @brief Computes the formfactor of a platonic octahedron
//!
//! @homepage https://jugit.fz-juelich.de/mlz/libformfactor
//! @license GNU General Public License v3 or higher (see LICENSE)
//! @copyright Forschungszentrum Jülich GmbH 2022
//! @author Joachim Wuttke, Scientific Computing Group at MLZ (see CITATION)
//
// ************************************************************************************************
#include "ff/Make.h"
#include <iostream>
constexpr double twopi = 6.28318530718;
//! Prints list t vs |F(q(t))| for a logarithmic range of t values
int main()
{
std::cout << "# Octahedral form factor, for different q scans\n";
ff::make::Octahedron octahedron(1.);
std::cout << "# q vs |F(q)| for q in direction 111, perpendicular to two faces\n";
for (double t = 0.2; t < 200; t *= 1.002) {
C3 q(t / sqrt(3), t / sqrt(3), t / sqrt(3));
std::cout << t << " " << std::abs(octahedron.formfactor(q)) << std::endl;
}
std::cout << std::endl;
std::cout << "# q vs |F(q)| for q in direction 110, perpendicular to two edges\n";
for (double t = 0.2; t < 200; t *= 1.002) {
C3 q(t / sqrt(2), t / sqrt(2), 0);
std::cout << t << " " << std::abs(octahedron.formfactor(q)) << std::endl;
}
std::cout << std::endl;
std::cout << "# q vs |F(q)| for q in direction 345, no special symmetry\n";
for (double t = 0.2; t < 200; t *= 1.002) {
C3 q(3 * t / sqrt(50), 4 * t / sqrt(50), 5 * t / sqrt(50));
std::cout << t << " " << std::abs(octahedron.formfactor(q)) << std::endl;
}
std::cout << std::endl;
std::cout << "# q vs |F(q)| for |q|=50, q on grand cercle through 111 and -1,-1,1 directions\n";
const C3 a1(1 / sqrt(3), 1 / sqrt(3), 1 / sqrt(3));
const C3 a2(-1 / sqrt(6), -1 / sqrt(6), 2 / sqrt(6));
for (double t = 0; t < twopi; t += twopi / 500) {
C3 q = 50. * (cos(t) * a1 + sin(t) * a2);
std::cout << t << " " << std::abs(octahedron.formfactor(q)) << std::endl;
}
std::cout << std::endl;
std::cout << "# q vs |F(q)| for |q|=50, q on grand cercle through 111 and -2,3,-5 directions\n";
const C3 b1(1 / sqrt(3), 1 / sqrt(3), 1 / sqrt(3));
const C3 b2(-8 / sqrt(98), 3 / sqrt(98), 5 / sqrt(98));
for (double t = 0; t < twopi; t += twopi / 500) {
C3 q = 50. * (cos(t) * b1 + sin(t) * b2);
std::cout << t << " " << std::abs(octahedron.formfactor(q)) << std::endl;
}
std::cout << std::endl;
}
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