DoubleHeisenbergSU2.h

Go to the documentation of this file.

#ifndef DOUBLEHEISENBERGMODELSU2
#define DOUBLEHEISENBERGMODELSU2
 
#include "symmetry/S1xS2.h"
#include "symmetry/SU2.h"
#include "bases/SpinBase.h"
#include "bases/FermionBase.h"
#include "models/DoubleHeisenbergObservables.h"
#include "Mpo.h"
#include "ParamReturner.h"
#include "Geometry2D.h" // from TOOLS
 
namespace VMPS
{
 
class DoubleHeisenbergSU2 : public Mpo<Sym::S1xS2<Sym::SU2<Sym::SpinSU2>,Sym::SU2<Sym::AltSpinSU2> > ,double>,
                            public DoubleHeisenbergObservables<Sym::S1xS2<Sym::SU2<Sym::SpinSU2>,Sym::SU2<Sym::AltSpinSU2> > >,
                            public ParamReturner
{
public:
    typedef Sym::S1xS2<Sym::SU2<Sym::SpinSU2>,Sym::SU2<Sym::AltSpinSU2> > Symmetry;
    MAKE_TYPEDEFS(DoubleHeisenbergSU2)
    
private:
    
    typedef Eigen::Index Index;
    typedef Symmetry::qType qType;
    typedef Eigen::Matrix<double,Eigen::Dynamic,Eigen::Dynamic> MatrixType;
    
    typedef SiteOperatorQ<Symmetry,MatrixType> OperatorType;
    
public:
    
    DoubleHeisenbergSU2() : Mpo(){};
    DoubleHeisenbergSU2 (const size_t &L, const vector<Param> &params, const BC &boundary=BC::OPEN, const DMRG::VERBOSITY::OPTION &VERB=DMRG::VERBOSITY::OPTION::ON_EXIT);
 
    template<typename Symmetry_> 
    static void set_operators (const std::vector<SpinBase<Symmetry_,0ul>> &B0, const std::vector<SpinBase<Symmetry_,1ul>> &B1, 
                               const ParamHandler &P,
                               PushType<SiteOperator<Symmetry_,double>,double>& pushlist, std::vector<std::vector<std::string>>& labellist, 
                               const BC boundary=BC::OPEN);
    
    static qarray<2> singlet (int N=0) {return qarray<2>{1,1};};
    static constexpr MODEL_FAMILY FAMILY = HEISENBERG;
    
    static const map<string,any> defaults;
    static const map<string,any> sweep_defaults;
};
 
const map<string,any> DoubleHeisenbergSU2::defaults = 
{
    {"D",2ul}, {"maxPower",2ul}, {"CYLINDER",false}, {"Ly",1ul}
};
 
const map<string,any> DoubleHeisenbergSU2::sweep_defaults = 
{
    {"max_alpha",100.}, {"min_alpha",1e-11}, {"lim_alpha",11ul}, {"eps_svd",1e-7},
    {"Dincr_abs", 2ul}, {"Dincr_per", 2ul}, {"Dincr_rel", 1.1},
    {"min_Nsv",1ul}, {"max_Nrich",-1},
    {"max_halfsweeps",30ul}, {"min_halfsweeps",6ul},
    {"Dinit",3ul}, {"Qinit",20ul}, {"Dlimit",500ul},
    {"tol_eigval",1e-6}, {"tol_state",1e-5},
    {"savePeriod",0ul}, {"CALC_S_ON_EXIT", true}, {"CONVTEST", DMRG::CONVTEST::VAR_2SITE}
};
 
DoubleHeisenbergSU2::
DoubleHeisenbergSU2 (const size_t &L, const vector<Param> &params, const BC &boundary, const DMRG::VERBOSITY::OPTION &VERB)
:Mpo<Symmetry> (L, Symmetry::qvacuum(), "", PROP::HERMITIAN, PROP::NON_UNITARY, boundary, VERB),
 DoubleHeisenbergObservables(L,params,DoubleHeisenbergSU2::defaults),
 ParamReturner(DoubleHeisenbergSU2::sweep_defaults)
{
    ParamHandler P(params,defaults);
    size_t Lcell = P.size();
    
    for (size_t l=0; l<N_sites; ++l)
    {
        N_phys += P.get<size_t>("Ly",l%Lcell);
        setLocBasis((B0[l].get_basis().combine(B1[l].get_basis())).qloc(),l);
    }
    
    this->set_name("DoubleHeisenberg");
    
    PushType<SiteOperator<Symmetry,double>,double> pushlist;
    std::vector<std::vector<std::string>> labellist;
    set_operators(B0, B1, P, pushlist, labellist, boundary);
    
    this->construct_from_pushlist(pushlist, labellist, Lcell);
    this->finalize(PROP::COMPRESS, P.get<size_t>("maxPower"));
    
    this->precalc_TwoSiteData();
}
 
template<typename Symmetry_>
void DoubleHeisenbergSU2::
set_operators (const std::vector<SpinBase<Symmetry_,0ul>> &B0, const std::vector<SpinBase<Symmetry_,1ul>> &B1, const ParamHandler &P, PushType<SiteOperator<Symmetry_,double>,double>& pushlist, std::vector<std::vector<std::string>>& labellist, const BC boundary)
{
    std::size_t Lcell = P.size();
    std::size_t N_sites = B0.size();
    if(labellist.size() != N_sites) {labellist.resize(N_sites);}
    
    for (std::size_t loc=0; loc<N_sites; ++loc)
    {
        stringstream ss;
        ss << "Ly=" << P.get<size_t>("Ly",loc%Lcell);
        labellist[loc].push_back(ss.str());
        
        auto push_full = [&N_sites, &loc, &B0, &B1, &P, &pushlist, &labellist, &boundary]
            (string xxxFull, string label,
             const vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > &first,
             const vector<vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > > &last,
             vector<double> factor) -> void
        {
            ArrayXXd Full = P.get<Eigen::ArrayXXd>(xxxFull);
            vector<vector<std::pair<size_t,double> > > R = Geometry2D::rangeFormat(Full);
            
            if (static_cast<bool>(boundary)) {assert(R.size() ==   N_sites and "Use an (N_sites)x(N_sites) hopping matrix for open BC!");}
            else                             {assert(R.size() >= 2*N_sites and "Use at least a (2*N_sites)x(N_sites) hopping matrix for infinite BC!");}
            
            for (size_t j=0; j<first.size(); j++)
            for (size_t h=0; h<R[loc].size(); ++h)
            {
                size_t range = R[loc][h].first;
                double value = R[loc][h].second;
                
                if (range != 0)
                {
                    vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > ops(range+1);
                    ops[0] = first[j];
                    for (size_t i=1; i<range; ++i)
                    {
                        ops[i] = OperatorType::outerprod(B0[(loc+i)%N_sites].Id(), B1[(loc+i)%N_sites].Id());
                    }
                    ops[range] = last[j][(loc+range)%N_sites];
                    pushlist.push_back(std::make_tuple(loc, ops, factor[j] * value));
                }
            }
            
            stringstream ss;
            ss << label << "(" << Geometry2D::hoppingInfo(Full) << ")";
            labellist[loc].push_back(ss.str());
        };
        
        if (P.HAS("Kfull"))
        {
            vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > first {OperatorType::outerprod(B0[loc].Sdag(0), B1[loc].Sdag(0))};
            vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > S_ranges(N_sites); for (size_t i=0; i<N_sites; i++)
            {S_ranges[i] = OperatorType::outerprod(B0[i].S(0), B1[i].S(0));}
            vector<vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > > last {S_ranges};
            push_full("Kfull", "Kᵢⱼ", first, last, {3.});
        }
        
        if (P.HAS("J1full"))
        {
            vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > first {kroneckerProduct(B0[loc].Sdag(0), B1[loc].Id())};
            vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > S_ranges(N_sites); for (size_t i=0; i<N_sites; i++) 
            {S_ranges[i] = kroneckerProduct(B0[i].S(0), B1[i].Id());}
            vector<vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > > last {S_ranges};
            push_full("J1full", "J1ᵢⱼ", first, last, {std::sqrt(3.)});
        }
        
        if (P.HAS("J2full"))
        {
            vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > first {kroneckerProduct(B0[loc].Id(), B1[loc].Sdag(0))};
            vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > S_ranges(N_sites); for (size_t i=0; i<N_sites; i++) 
            {S_ranges[i] = kroneckerProduct(B0[i].Id(), B1[i].S(0));}
            vector<vector<SiteOperatorQ<Symmetry_,Eigen::MatrixXd> > > last {S_ranges};
            push_full("J2full", "J2ᵢⱼ", first, last, {std::sqrt(3.)});
        }
    }
}
 
} //end namespace VMPS
#endif