Cumulant.h

/*
   CheMPS2: a spin-adapted implementation of DMRG for ab initio quantum chemistry
   Copyright (C) 2013-2016 Sebastian Wouters

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with this program; if not, write to the Free Software Foundation, Inc.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#ifndef CUMULANT_CHEMPS2_H
#define CUMULANT_CHEMPS2_H

#include "ThreeDM.h"
#include "TwoDM.h"

namespace CheMPS2{
   class Cumulant{

      public:


         static double gamma4_ham(const Problem * prob, const ThreeDM * the3DM, const TwoDM * the2DM, const int i, const int j, const int k, const int l, const int p, const int q, const int r, const int s);
         

         static void gamma4_fock_contract_ham(const Problem * prob, const ThreeDM * the3DM, const TwoDM * the2DM, double * fock, double * result);
         
      private:
      
         // Get the second order cumulant \f$ \Lambda^2_{ijpq} \f$, using HAM indices
         static double lambda2_ham(const TwoDM * the2DM, const int i, const int j, const int p, const int q);
         
   };
}

#endif