AC.h

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/*
 * AC.h
 *
 *  Created on: Dec 13, 2016
 *      Author: msahre
 */
 
#ifndef SRC_APPS_CHEM_AC_H_
#define SRC_APPS_CHEM_AC_H_
 
#include <madness/world/MADworld.h>
#include <madness/mra/mra.h>
#include <madness/mra/funcplot.h>
#include <exception>
#include <iterator>
#include <list>
#include<madness/chem/SCF.h>
 
namespace madness {
 
 
 
/// Needed information about atom to compute asymptotic correction
template<unsigned long int NDIM>
struct atom_information{
 
    /// Coordinates of nucleus
    Vector<double,NDIM> coord;
 
    /// Interval boundaries, in which exchange correlation potential (<R1) and 1/r potential (>R2) are used
    double R1;
    double R2;
 
    /// Nuclear charge
    int charge;
 
    /// Computes the distance between electron and nucleus
    /// @param[in] elec: position of electron
    /// @param[in] nuc: position of nucleus
    /// @param[out] distance: distance between electron and nucleus
    double get_distance(Vector<double,NDIM> elec, Vector<double,NDIM> nuc) const{
        double distance = 0.0;
        for(unsigned i = 0; i < NDIM; i++){
            distance += (elec[i]-nuc[i])*(elec[i]-nuc[i]);
        }
        distance = sqrt(distance);
 
        return distance;
    }
 
    template <typename Archive>
    void serialize(Archive& ar) {
        ar &  coord& R1&  R2& charge;
    }
 
};
 
/// Creates vector of atom_information for the given molecule
/// @param[in] molecule: the molecule
/// @param[out] : the vector containing the atom_information for each atom in the molecule
std::vector<atom_information<3> > make_atom_vec(const Molecule& molecule, double R1_,double R2_);
 
/// collection of slater radii needed to calculate R1 and R2; The Journal of Chemical Physics 41, 3199 (1964); doi: 10.1063/1.1725697
/// @param[in] atomic_number: atomic_number of atom
/// @param[out] : slater radius corresponding to atomic_number
double slater_radius(int atomic_number);
 
 
 
 
/// Contains all the parameters for the asymptotic correction
template<unsigned long int NDIM>
struct ACParameters{
    std::vector< atom_information<NDIM> > atoms_;
    bool use_mult_; /// set true to use multipole approximation
    double e_ion_; /// ionisation energy of corresponding ion without ac
    double eh_; /// energy of the homo without ac
    double R1_; /// lower boundary interpolation area
    double R2_; /// upper boundary for interpolation area
    double dft_coefficient_; /// dft coefficient for hybrid functionals (=1.0 for non hybrid)
    int num_elec_; /// number of electrons
    std::string interpolation_scheme_; /// scheme for interpolation between xc-functional and 1/r-potential
 
 
    template <typename Archive>
    void serialize(Archive& ar) {
        ar & atoms_ & e_ion_ & eh_ & R1_ & R2_ & dft_coefficient_ & num_elec_ & interpolation_scheme_;
    }
 
    ACParameters(){
        use_mult_ = false;
        e_ion_ = 0.0;
        eh_ = 0.0;
        R1_ = 3.0;
        R2_ = 4.0;
        interpolation_scheme_ = "linear";
        num_elec_=-1;
        dft_coefficient_=0.0;
    }
 
    bool initialize(Molecule molecule, std::string ac_data, double dft_coeff, double tot_charge){
        if(ac_data=="none"){
            return false;
        }else{
        dft_coefficient_ = dft_coeff;
 
        std::stringstream sac_data(ac_data);
        std::string word;
 
        while (sac_data >> word) {
            std::transform(word.begin(), word.end(), word.begin(), ::toupper);
            if(word=="MULT"){
                use_mult_ = true;
            } else if(word == "EION") {
                sac_data >> e_ion_;
            } else if(word == "EHOMO"){
                sac_data >> eh_;
            } else if(word == "R1"){
                sac_data >> R1_;
            } else if(word == "R2"){
                sac_data >> R2_;
            } else if(word == "INTERPOL"){
                sac_data >> interpolation_scheme_;
            } else {
                std::cout << "Invalid entry in ac line\n";
                //MADNESS_ASSERT("Invalid ac_data!\n", 1);
            }
        }
        atoms_ = make_atom_vec(molecule, R1_, R2_);
        num_elec_ = molecule.total_nuclear_charge() - tot_charge;
        return true;
        }
    }
 
    ACParameters(const ACParameters &other)
    : atoms_(other.atoms_), use_mult_(other.use_mult_), e_ion_(other.e_ion_),
      eh_(other.eh_), R1_(other.R1_), R2_(other.R2_), dft_coefficient_(other.dft_coefficient_),
      num_elec_(other.num_elec_), interpolation_scheme_(other.interpolation_scheme_) {}
 
    void print(World& world){
        if(world.rank()==0){
        std::cout << "\nAsymptotic correction parameters\n";
        std::cout << "---------------------------------------\n";
        std::cout << "Atom vector is not empty: " << !atoms_.empty() << "\n";
        std::cout << "Using multipole approximation: " << use_mult_ << "\n";
        std::cout << "Number of electrons = " << num_elec_ << "\n";
        std::cout << "Ionisation energy = " << e_ion_ << "\n";
        std::cout << "E(HOMO) = " << eh_ << "\n";
        std::cout << "R1 = " << R1_ << "\n";
        std::cout << "R2 = " << R2_ << "\n";
        std::cout << "DFT coefficient = " << dft_coefficient_ << "\n";
        std::cout << "Interpolation scheme = " << interpolation_scheme_ << "\n";
        }
    }
 
    void check(World& world){
        if(atoms_.empty()) { MADNESS_EXCEPTION("Failed to initialize AC object!",1); }
        else if(num_elec_ <0) { MADNESS_EXCEPTION("Negative number of electrons!",1); }
        else if(e_ion_ < 0) { MADNESS_EXCEPTION("Ionisation energy is negative!",1); }
        else if(eh_>0) { MADNESS_EXCEPTION("Energy of homo is positive!",1); }
        else if(R1_ == 0.0 or R2_ == 0.0) std::cout << "\n\nWARNING: R1 or R2 is zero!\n\n";
        else if(interpolation_scheme_ != "linear" and interpolation_scheme_ != "constant") std::cout << "\n\nWARNING: Unknown interpolation scheme, using linear interpolation instead\n\n!";
        else if(world.rank()==0) std::cout << "AC object was initialized succesfully!\n\n";
    }
 
};
 
/// Functor for the correction factor, which is multiplied with the exchange correlation potential
template<unsigned long int NDIM>
class int_factor_functor : public FunctionFunctorInterface<double,NDIM>{
 
public:
    using FunctionFunctorInterface<double,NDIM>::operator();
 
    int_factor_functor(){}
    //int_factor_functor(std::vector<atom_information<NDIM> > atoms, std::string interpolation): atoms(atoms), intpol_scheme(interpolation){}
 
    int_factor_functor(const ACParameters<NDIM>& ac_param) : ac_param_(ac_param) {}
 
    //int_factor_functor(std::string interpolation) : intpol_scheme(interpolation) {}
 
 
 
    /// Computes correction factor for exchange correlation potential
    /// @param[in] r: position of the electron
    /// @param[out] : correction factor for exchange correlation potential at position r
    double operator ()(const Vector<double, NDIM> &r)const{
 
        // distance between electron and nuclues
        double d = 0.0;
 
        bool inside_R1 = false;
        std::vector<atom_information<NDIM> > between;
 
        // get position of electron relative to nuclei, to compute right correction factor
        for(const auto& x:ac_param_.atoms_){
            d = get_distance(r, x.coord);
            // check if d<R1 for at least one nucleus
            if(d<x.R1) {
                inside_R1 = true;
                break;
            }
            // push_back index of nucleus for which electron is inbetween
            if(x.R1 < d and d < x.R2) {
                between.push_back(x);
            }
        }
 
        // compute correction factor
        // at least for one nucleus r<R1
        if(inside_R1){
            return 1.0;}
        // all nuclei r>R2
        else if(between.empty()){
            return 0.0;}
        // for N nuclei R1<r<R2
        else {
            return int_factor(r, between);
        }
    }
 
    /// Computes correction factor for the exchange correlation potential if electron position is between R1 and R2
    /// @param[in] r: position of electron
    /// @param[in] between: vector of the atom_information of all atoms for that electron position is between R1 and R2
    /// @param[out] int_factor: correction factor
    double int_factor(const Vector<double, NDIM> &r, std::vector<atom_information<NDIM> > between) const{
        // Do not forget to add interpolation scheme to ACparameters check()
        if(ac_param_.interpolation_scheme_=="constant"){
            return 0.5;
        }
        else{
            double int_factor = 0.0;
            for(const auto& x:between){
                // linear interpolation scheme between R1 and R2
                int_factor += (- get_distance(r,x.coord) + x.R2)/(x.R2-x.R1);
                //int_factor += 0.5*(erf(-(get_distance(r, x.coord)-5.0))+1.0);
            }
            int_factor = int_factor/(double(between.size()));
            return int_factor;
        }
    }
 
private:
    /// Computes the distance between electron and nucleus
    /// @param[in] elec: position of electron
    /// @param[in] nuc: position of nucleus
    /// @param[out] distance: distance between electron and nucleus
    double get_distance(Vector<double,NDIM> elec, Vector<double,NDIM> nuc) const{
        double distance = 0.0;
        for(unsigned i = 0; i < NDIM; i++){
            distance += (elec[i]-nuc[i])*(elec[i]-nuc[i]);
        }
        distance = sqrt(distance);
 
        return distance;
    }
 
    /// Parameter for the asymtotic correction
    const ACParameters<NDIM> &ac_param_;
 
};
 
/// Functor for the 1/r potential to induce the correct asymptotic behaviour of the exchange correlation potential
template<unsigned long int NDIM>
class lr_pot_functor : public FunctionFunctorInterface<double,NDIM>{
 
public:
    using FunctionFunctorInterface<double,NDIM>::operator();
 
    lr_pot_functor(){}
    //lr_pot_functor(std::vector<atom_information<NDIM> > atoms, double dft_coeff_, std::string interpolation): atoms(atoms), dft_coeff(dft_coeff_), intpol_scheme(interpolation){}
 
    lr_pot_functor(const ACParameters<NDIM> & ac_param): ac_param_(ac_param){}
 
    /// Computes 1/r potential weighted by a correction factor
    /// @param[in] r: position of the electron (density)
    /// @param[out]: 1/r potential weighted by a correction factor
    double operator ()(const Vector<double, NDIM> &r)const{
        // distance between electron and nuclues
        double d = 0.0;
        bool inside_R1 = false;
        std::vector<atom_information<NDIM> > between;
 
        // get position of electron relative to nuclei, to compute right correction factor
        for(const auto& x:ac_param_.atoms_){
 
            d = get_distance(r, x.coord);
            // check if d<R1 for at least one nucleus
            if(d<x.R1) {
                inside_R1 = true;
                break;
            }
 
            // push_back index of nucleus for which electron is inbetween
            if(x.R1 < d and d < x.R2) {
                between.push_back(x);
            }
 
        }
 
        // compute correction factor
        // at least for one nucleus r<R1
        if(inside_R1){return 0.0;} // return 0.0;
 
        // all nuclei r>R2
        else if(between.empty()){return 1.0*potential(r);} // 1.0*potential(r)+E_ion+E_homo
 
        // for N nuclei R1<r<R2
        else {return (int_factor(r, between))*potential(r);}
    }
 
private:
    /// Computes the distance between electron and nucleus
    /// @param[in] elec: position of electron
    /// @param[in] nuc: position of nucleus
    /// @param[out] distance: distance between electron and nucleus
    double get_distance(Vector<double,NDIM> elec, Vector<double,NDIM> nuc) const{
        double distance = 0.0;
        for(unsigned i = 0; i < NDIM; i++){
            distance += (elec[i]-nuc[i])*(elec[i]-nuc[i]);
        }
        distance = sqrt(distance);
 
        return distance;
    }
 
    /// Multipole approximation of the 1/r potential for electron coordinate > R1 for all nuclei
    /// @param[in] r: coordinate of the electron
    /// @param[out] : potential at given coordinate r
    double potential(const Vector<double, NDIM> &r) const{
        double pot = 0.0;
        for(const auto& x:ac_param_.atoms_){
            pot += double(x.charge)/get_distance(r, x.coord);
        }
        return (-ac_param_.dft_coefficient_*pot/ac_param_.num_elec_);
    }
 
    /// Computes correction factor for the 1/r potential if electron position is between R1 and R2
    /// @param[in] r: position of electron
    /// @param[in] between: vector of the atom_information of all atoms for that electron position is between R1 and R2
    /// @param[out] int_factor: correction factor
    double int_factor(const Vector<double, NDIM> &r, std::vector<atom_information<NDIM> > between) const{
        int_factor_functor<NDIM> interpolation(ac_param_);
        double int_factor = interpolation.int_factor(r, between);
        return (1.0 - int_factor);
    }
 
    /// Parameter for the asymtotic correction
    const ACParameters<NDIM> &ac_param_;
};
 
/// computes the corrected exchange correlation potential using the multipole approximation
 
template<unsigned long int NDIM>
struct UnaryOpStructure {
 
    UnaryOpStructure(const std::shared_ptr<FunctionFunctorInterface<double,NDIM> > f_, const std::shared_ptr<FunctionFunctorInterface<double,NDIM> > f2_) :
        f(f_), f2(f2_),
        cdata(FunctionCommonData<double,NDIM>::get(FunctionDefaults<NDIM>::get_k())){};
 
    /// computes the corrected potential (weighting with correction factor and adding of 1/r potential)
    /// @param[in] t: uncorrected exchange correlation potential
    /// @param[out] t: corrected exchange correlation potential
    void operator()(const Key<NDIM>& key, Tensor<double>& t) const {
        Tensor<double> intpol(t.ndim(),t.dims());//madness::copy(t);
        Tensor<double> lrpot(t.ndim(),t.dims());
        const Tensor<double>& qp =cdata.quad_x;
        fcube(key,(*f),qp,intpol);
        fcube(key,(*f2),qp,lrpot);
 
        // multiply xc-functional with interpolation factor
        t.emul(intpol);
        // add 1/r correction to xc-functional
        t= t + lrpot;
    }
    /// shared pointer to object of int_factor_functor
    std::shared_ptr<FunctionFunctorInterface<double,NDIM> > f;
    /// shared pointer to object of lr_pot_functor
    std::shared_ptr<FunctionFunctorInterface<double,NDIM> > f2;
    FunctionCommonData<double,NDIM> cdata;
    template <typename Archive> void serialize(Archive& ar) {}
};
 
/// computes the corrected exchange correlation potential using the hartree potential
 
template<unsigned long int NDIM>
struct BinaryOpStructure {
    /// necessary to compile the program without getting a strange error i dont understand
    BinaryOpStructure(): f(NULL), cdata(FunctionCommonData<double,NDIM>::get(FunctionDefaults<NDIM>::get_k())) {}
 
    BinaryOpStructure(const std::shared_ptr<FunctionFunctorInterface<double,NDIM> > f_) :
        f(f_),
        cdata(FunctionCommonData<double,NDIM>::get(FunctionDefaults<NDIM>::get_k())){};
 
    BinaryOpStructure(const BinaryOpStructure<NDIM> &other) : f(other.f), cdata(other.cdata) {}
 
    /// computes the corrected potential (weighting with correction factor and adding of 1/r potential)
    /// @param[in] t: uncorrected exchange correlation potential
    /// @param[out] t: corrected exchange correlation potential
    void operator()(const Key<NDIM>& key, Tensor<double>& result, const Tensor<double>& vxc, const Tensor<double>& vhartree) const {
 
        if(f.get()==NULL) MADNESS_EXCEPTION("NULL Pointer in BinaryOpStructure of AC",1);
 
        Tensor<double> intpol(result.ndim(),result.dims());//madness::copy(t);
        Tensor<double> lrpot(result.ndim(),result.dims());
        const Tensor<double>& qp =cdata.quad_x;
        fcube(key,(*f),qp,intpol);
 
        // exchange correlation potential weighted by correction factor
        Tensor<double> tmp1 = madness::copy(vxc).emul(intpol);
        // hartree potential pot weighted by correction factor
        Tensor<double> tmp2 = madness::copy(vhartree).emul(intpol);
        Tensor<double> tmp3 = madness::copy(vhartree);
        // corrected potential
        result = tmp1 - tmp2 + tmp3;
    }
 
    /// shared pointer to object of int_factor_functor
    std::shared_ptr<FunctionFunctorInterface<double,NDIM> > f;
    FunctionCommonData<double,NDIM> cdata;
    template <typename Archive> void serialize(Archive& ar) {}
};
 
/// Asymptotic correction for DFT. In the correction the xc-potential is replaced by an 1/r term far away from the nuclei
/// to give the correct asymptotic behavior. Close to the nuclei the standard xc-potential is used. The transition between
/// the different potentials is achieved via a linear interpolation.
/// for more information see: Molecular Physics, Vol. 103, No. 2–3, 20 January–10 February 2005, 413–424;
/// The Journal of Chemical Physics 109, 10180 (1998); doi: 10.1063/1.477711;
/// Molecular Physics, 1999, VOL.97, No. 7, 859-868
template<unsigned long int NDIM>
class AC{
private:
 
    /// Parameter for the asymtotic correction
    ACParameters<NDIM> ac_param_;
    bool initialized_=false;
    double shift()const{return (-ac_param_.e_ion_-ac_param_.eh_);}
 
public:
    bool initialized()const{return initialized_;}
    AC() = default;
 
   AC(const ACParameters<NDIM>& ac_param): ac_param_(ac_param) {}
 
   /// defunct: the `ac_data` calculation parameter was removed, so this always
   /// initializes as if `ac_data none` had been given
   AC(World &world, std::shared_ptr<SCF> calc){
       const std::string ac_data="none";
       if(world.rank()==0){
           initialized_=ac_param_.initialize(calc->molecule, ac_data, 1.0-calc->xc.hf_exchange_coefficient(), calc->param.charge());
       }
       world.gop.broadcast_serializable(initialized_,0);
       world.gop.broadcast_serializable(ac_param_, 0);
//     ac_param_.print(world);
       if(ac_data!="none") ac_param_.check(world);
   }
 
   AC(const AC& other): ac_param_(other.ac_param_){}
 
   /// /// correction of the exchange correlation potential using the multipole approximation to describe asymptotic behaviour
   /// @param[in] xc_functional: uncorrected (standard) exchange correlation potential
   /// @param[out] : corrected exchange correlation potential
   Function<double,NDIM> apply(Function<double,NDIM> xc_functional)const{
       MADNESS_ASSERT(initialized());
       std::cout << "Apply AC Scheme with multipole approximation\n";
       // fast return
       if(ac_param_.atoms_.empty()){
           std::cout << "OR NOT -- EMPTY VECTOR ATOMS!!!\n";
           return xc_functional;
       }
 
       if(ac_param_.dft_coefficient_ < 0.0) { MADNESS_EXCEPTION("DFT coefficient is negative!",1); }
       if(ac_param_.dft_coefficient_ == 0.0) { MADNESS_EXCEPTION("DFT coefficient is zero. This is no DFT calculation!\n",1); }
 
       // shift of the exchange correlation potential to get the correct asymptotic behaviour
       xc_functional = xc_functional + shift();
       // pointer on interpolation factor and long range potential (1/r pot)
       std::shared_ptr<FunctionFunctorInterface<double, NDIM> > int_ptr(new int_factor_functor<NDIM>(ac_param_));
       std::shared_ptr<FunctionFunctorInterface<double, NDIM> > lr_pot_ptr(new lr_pot_functor<NDIM>(ac_param_));
 
        // compute interpolation and long range potential
        UnaryOpStructure<NDIM> U_total(int_ptr,lr_pot_ptr);
 
        // apply correction on xc functional
        xc_functional.template unaryop<UnaryOpStructure<NDIM> >(U_total);
        //plot_plane( xc_functional, "test_total");
        return xc_functional;
   }
 
   /// correction of the exchange correlation potential using the hartree potential to describe asymptotic behaviour
   /// @param[in] xc_functional: uncorrected (standard) exchange correlation potential
   /// @param[in] v_hartree: potential to describe asymptotic behaviour
   /// @param[out] : corrected exchange correlation potential
   Function<double,NDIM> apply(Function<double,NDIM> xc_functional, const Function<double,NDIM> v_hartree)const{
       MADNESS_ASSERT(initialized());
       if(ac_param_.use_mult_) return apply(xc_functional);
       //else return apply_potential(xc_functional, v_hartree);
       std::cout << "Apply AC Scheme with hartree potential\n";
       // fast return
       if(ac_param_.atoms_.empty()){
           std::cout << "OR NOT -- EMPTY VECTOR ATOMS!!!\n";
           return xc_functional;
       }
       // shift of the exchange correlation potential to get the correct asymptotic behaviour
       xc_functional = xc_functional + shift();
 
       // pointer on interpolation factor and long range potential
       std::shared_ptr<FunctionFunctorInterface<double, NDIM> > int_ptr(new int_factor_functor<NDIM>(ac_param_));
 
       // compute interpolation and long range potential
       BinaryOpStructure<NDIM> U_total(int_ptr);
       xc_functional = binary_op<double,double,BinaryOpStructure<NDIM>,NDIM >(xc_functional, v_hartree, U_total);
 
       return xc_functional;
   }
 
};
 
}// end namespace
 
#endif /* SRC_APPS_CHEM_AC_H_ */