Function automatic_alpha

cpp_core/src/ewald.cpp:20–24

}

double automatic_alpha(const Lattice& lattice) {
    // Characteristic inverse length from cell volume.
    const double l_char = std::cbrt(std::max(lattice.volume, 1e-12));
    return 5.0 / l_char;
}

double compute_real_cutoff(double alpha_bohr_inv, double tol) {
    const double clamped_tol = std::max(1e-18, std::min(1e-4, tol));