xc_functional.hpp

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// Copyright (c) 2013-2016 Anton Kozhevnikov, Thomas Schulthess
// All rights reserved.
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/** \file xc_functional.hpp
 *
 *  \brief Contains implementation of sirius::XC_functional class.
 */
 
#ifndef __XC_FUNCTIONAL_HPP__
#define __XC_FUNCTIONAL_HPP__
 
#include <xc.h>
#include <string.h>
#include "core/r3/r3.hpp"
#include "xc_functional_base.hpp"
#include "core/fft/fft.hpp"
#if defined(SIRIUS_USE_VDWXC)
#include <vdwxc.h>
#if SIRIUS_HAVE_VDWXC_MPI
#include <vdwxc_mpi.h>
#endif
#endif
 
namespace sirius {
 
/// Interface class to Libxc.
class XC_functional : public XC_functional_base
{
    private:
        // I can not use a generic void pointer because xc_func_type is a structure
        // while wdv_functional_ is a pointer over structure.
#if defined(SIRIUS_USE_VDWXC)
        vdwxc_data handler_vdw_{nullptr};
        bool vdw_functional_{false};
#endif
        /* forbid copy constructor */
        XC_functional(const XC_functional& src) = delete;
 
        /* forbid assignment operator */
        XC_functional& operator=(const XC_functional& src) = delete;
 
    public:
 
      /* we need the context because libvdwxc asks for lattice vectors and fft parameters */
      XC_functional(spfft::Transform const& fft__, r3::matrix<double> const& lattice_vectors__,
                    const std::string libxc_name__, int num_spins__)
          : XC_functional_base(libxc_name__, num_spins__)
    {
 
#if defined(SIRIUS_USE_VDWXC)
            /* return immediately if the functional_base class is initialized */
            if (this->libxc_initialized_) {
                return;
            }
 
            /* test if have van der walls functionals types */
 
            bool test = (libxc_name_ == "XC_FUNC_VDWDF");
            test = test || (libxc_name_ == "XC_FUNC_VDWDF2");
            test = test || (libxc_name_ == "XC_FUNC_VDWDFCX");
 
            int func_ = -1;
 
            if (libxc_name__ == "XC_FUNC_VDWDF") {
                func_ = FUNC_VDWDF;
            }
 
            if (libxc_name__ == "XC_FUNC_VDWDF2") {
                func_ = FUNC_VDWDF2;
            }
 
            if (libxc_name__ == "XC_FUNC_VDWDFCX") {
                func_ = FUNC_VDWDFCX;
            }
 
            if (test) {
                if (num_spins__ == 1) {
                    // non magnetic case
                    handler_vdw_ = vdwxc_new(func_);
                } else {
                    // magnetic case
                    handler_vdw_ = vdwxc_new_spin(func_);
                }
 
                if (!handler_vdw_) {
                    std::stringstream s;
                    s << "VDW functional lib could not be initialized";
                    RTE_THROW(s);
                }
 
                double v1[3] = { lattice_vectors__(0, 0), lattice_vectors__(1, 0), lattice_vectors__(2, 0) };
                double v2[3] = { lattice_vectors__(0, 1), lattice_vectors__(1, 1), lattice_vectors__(2, 1) };
                double v3[3] = { lattice_vectors__(0, 2), lattice_vectors__(1, 2), lattice_vectors__(2, 2) };
                vdwxc_set_unit_cell(handler_vdw_,
                                    fft__.dim_x(),
                                    fft__.dim_y(),
                                    fft__.dim_z(),
                                    v1[0], v1[1], v1[2],
                                    v2[0], v2[1], v2[2],
                                    v3[0], v3[1], v3[2]);
                if (mpi::Communicator(fft__.communicator()).size() == 1) {
                    vdwxc_init_serial(handler_vdw_);
                } else {
#if SIRIUS_HAVE_VDWXC_MPI
                    vdwxc_init_mpi(handler_vdw_, fft__.communicator());
#else
                    vdwxc_init_serial(handler_vdw_);
#endif
                }
                vdw_functional_ = true;
                return;
            } else {
                /* it means that the functional does not exist either in vdw or xc libraries */
                std::stringstream s;
                s << "XC functional " << libxc_name__ << " is unknown";
                RTE_THROW(s);
            }
#else
            if (this->libxc_initialized_) {
                return;
            } else {
                /* it means that the functional does not exist either in vdw or xc libraries */
                std::stringstream s;
                s << "XC functional " << libxc_name__ << " is unknown";
                RTE_THROW(s);
            }
#endif /* SIRIUS_USE_VDWXC */
        }
 
    XC_functional(XC_functional&& src__)
        :XC_functional_base(std::move(src__))
        {
#if defined(SIRIUS_USE_VDWXC)
            this->handler_vdw_ = src__.handler_vdw_;
            this->vdw_functional_ = src__.vdw_functional_;
            src__.vdw_functional_ = false;
#endif
        }
 
    ~XC_functional()
        {
#if defined(SIRIUS_USE_VDWXC)
            if (this->vdw_functional_) {
                vdwxc_finalize(&this->handler_vdw_);
                this->vdw_functional_ = false;
                return;
            }
#endif
        }
 
        const std::string refs() const
        {
#if defined(SIRIUS_USE_VDWXC)
            std::stringstream s;
            if (vdw_functional_) {
                s << "==============================================================================\n";
                s << "                                                                              \n";
                s << "Warning : these functionals should be used in combination with GGA functionals\n";
                s << "                                                                              \n";
                s << "==============================================================================\n";
                s << "\n";
                s << "A. H. Larsen, M. Kuisma, J. Löfgren, Y. Pouillon, P. Erhart, and P. Hyldgaard, ";
                s << "Modelling Simul. Mater. Sci. Eng. 25, 065004 (2017) (10.1088/1361-651X/aa7320)\n";
                return s.str();
            }
#endif
            return XC_functional_base::refs();
        }
 
        int family() const
        {
#if defined(SIRIUS_USE_VDWXC)
            if (this->vdw_functional_ == true) {
                return XC_FAMILY_UNKNOWN;
            }
#endif
            return XC_functional_base::family();
        }
 
        bool is_vdw() const
        {
#if defined(SIRIUS_USE_VDWXC)
            return this->vdw_functional_;
#else
            return false;
#endif
        }
 
    void vdw_update_unit_cell(spfft::Transform const& fft__, r3::matrix<double> const& lattice_vectors__)
    {
        #ifdef SIRIUS_USE_VDWXC
        if(is_vdw()) {
            double v1[3] = {lattice_vectors__(0, 0), lattice_vectors__(1, 0), lattice_vectors__(2, 0)};
            double v2[3] = {lattice_vectors__(0, 1), lattice_vectors__(1, 1), lattice_vectors__(2, 1)};
            double v3[3] = {lattice_vectors__(0, 2), lattice_vectors__(1, 2), lattice_vectors__(2, 2)};
 
            vdwxc_set_unit_cell(handler_vdw_, fft__.dim_x(), fft__.dim_y(), fft__.dim_z(), v1[0], v1[1], v1[2], v2[0],
                                v2[1], v2[2], v3[0], v3[1], v3[2]);
        }
        #endif
    }
 
        int kind() const
        {
 
#if defined(SIRIUS_USE_VDWXC)
            if (this->vdw_functional_ == true) {
                return -1;
            }
#endif
            return XC_functional_base::kind();
        }
 
#if defined(SIRIUS_USE_VDWXC)
    /// get van der walls contribution for the exchange term
    void get_vdw(double* rho,
                 double* sigma,
                 double* vrho,
                 double* vsigma,
                 double* energy__)
        {
            if (!is_vdw()) {
                RTE_THROW("Error wrong vdw XC");
            }
            energy__[0] = vdwxc_calculate(handler_vdw_, rho, sigma, vrho, vsigma);
        }
 
    /// get van der walls contribution to the exchange term magnetic case
    void get_vdw(double *rho_up, double *rho_down,
                 double *sigma_up, double *sigma_down,
                 double *vrho_up, double *vrho_down,
                 double *vsigma_up, double *vsigma_down,
                 double *energy__)
        {
            if (!is_vdw()) {
                RTE_THROW("Error wrong XC");
            }
 
            energy__[0] = vdwxc_calculate_spin(handler_vdw_, rho_up, rho_down,
                                               sigma_up , sigma_down,
                                               vrho_up, vrho_down,
                                               vsigma_up, vsigma_down);
        }
#endif
};
 
}
 
#endif // __XC_FUNCTIONAL_H__