test_xc6.cpp

#include "../xc_functional.h"
#include "../libxc_abacus.h"
#include "gtest/gtest.h"
#include "xctest.h"
#include "../exx_info.h"
#include <cmath>
#include <iostream>
#include <iomanip>

namespace ModuleBase
{
    void WARNING_QUIT(const std::string &file,const std::string &description) {exit(1);}
    void TITLE(const std::string &class_function_name,bool disable){};
    void TITLE(const std::string &class_name,const std::string &function_name,bool disable){};
}

namespace GlobalV
{
    std::string BASIS_TYPE = "";
    bool CAL_STRESS = false;
    int CAL_FORCE = 0;
    int NSPIN = 1;
}

namespace GlobalC
{
    Exx_Info exx_info;
}

class XCTest_SCANL_Laplacian : public XCTest
{
    protected:
        double e_base, v1_base, v2_base, v3_base;
        double e_modified, v1_modified, v2_modified, v3_modified;
        double e_scaled, v1_scaled, v2_scaled, v3_scaled;

        void SetUp()
        {
            XC_Functional::set_xc_type("MGGA_X_SCANL+MGGA_C_SCANL");

            const double rho = 0.17E+01;
            const double grho = 0.81E-11;
            const double tau = 0.02403590412;
            const double lapl_base = 0.15E+01;
            double hybrid_alpha = 0.0;

            XC_Functional_Libxc::tau_xc(
                XC_Functional::get_func_id(),
                rho, grho, lapl_base, tau,
                e_base, v1_base, v2_base, v3_base, hybrid_alpha
            );

            XC_Functional_Libxc::tau_xc(
                XC_Functional::get_func_id(),
                rho, grho, lapl_base + 1.0, tau,
                e_modified, v1_modified, v2_modified, v3_modified, hybrid_alpha
            );

            XC_Functional_Libxc::tau_xc(
                XC_Functional::get_func_id(),
                rho, grho, 2.0 * lapl_base, tau,
                e_scaled, v1_scaled, v2_scaled, v3_scaled, hybrid_alpha
            );
        }
};

TEST_F(XCTest_SCANL_Laplacian, laplacian_affects_energy)
{
    EXPECT_NE(e_base, e_modified);
    EXPECT_NE(e_base, e_scaled);

    std::cout << std::scientific << std::setprecision(15);
    std::cout << "\n=== SCAN Laplacian Sensitivity Test ===" << std::endl;
    std::cout << "Base Laplacian:    " << 0.15E+01 << std::endl;
    std::cout << "  E_xc =           " << e_base << std::endl;
    std::cout << "  dE/dlapl ≈       " << (e_modified - e_base) / 1.0 << std::endl;
    std::cout << "Modified Laplacian:" << 0.15E+01 + 1.0 << std::endl;
    std::cout << "  E_xc =           " << e_modified << std::endl;
    std::cout << "  Delta E =        " << e_modified - e_base << std::endl;
    std::cout << "Scaled Laplacian:  " << 2.0 * 0.15E+01 << std::endl;
    std::cout << "  E_xc =           " << e_scaled << std::endl;
    std::cout << "  Delta E =        " << e_scaled - e_base << std::endl;
    std::cout << "========================================" << std::endl;
}