!***********************************************************************
! This file is part of OpenMolcas.                                     *
!                                                                      *
! OpenMolcas is free software; you can redistribute it and/or modify   *
! it under the terms of the GNU Lesser General Public License, v. 2.1. *
! OpenMolcas is distributed in the hope that it will be useful, but it *
! is provided "as is" and without any express or implied warranties.   *
! For more details see the full text of the license in the file        *
! LICENSE or in <http://www.gnu.org/licenses/>.                        *
!                                                                      *
! Copyright (C) Ben Swerts                                             *
!               2016, Liviu Ungur                                      *
!***********************************************************************

subroutine FragPMmG( &
#                   define _CALLING_
#                   include "mem_interface.fh"
                   )
!***********************************************************************
!  Object: to compute the number of reals the kernel routine will      *
!          need for the computation of a matrix element between two    *
!          cartesian Gaussian functions with the total angular momentum*
!          of la and lb (la=0 s-function, la=1 p-function, etc.)       *
!          lr is the order of the operator (this is only used when the *
!          integrals are computed with the Hermite-Gauss quadrature).  *
!                                                                      *
!  Called from: OneEl_g                                                *
!                                                                      *
!  author: Ben Swerts                                                  *
!  modified: Liviu Ungur                                               *
!  based on PrjMmG                                                     *
!                                                                      *
!***********************************************************************

use Basis_Info, only: dbsc, nCnttp, Shells
use Definitions, only: iwp

implicit none
#include "mem_interface.fh"
integer(kind=iwp) :: nOrder, maxDensSize, iCnttp, jCnttp, iAng, jAng, iShll, jShll, ip, nac, ncb, nExpi, nExpj, nBasisi, nBasisj

nOrder = 0
Mem = 0
maxDensSize = 0
! largest possible fragment energy weighted density matrix
do iCnttp=1,nCnttp
  if (dbsc(iCnttp)%nFragType > 0) maxDensSize = max(maxDensSize,dbsc(iCnttp)%nFragDens*(dbsc(iCnttp)%nFragDens+1)/2)
end do

do iCnttp=1,nCnttp
  if (.not. dbsc(iCnttp)%Frag) cycle

  do iAng=0,dbsc(iCnttp)%nVal-1
    iShll = dbsc(iCnttp)%iVal+iAng
    nExpi = Shells(iShll)%nExp
    nBasisi = Shells(iShll)%nBasis
    if (nExpi == 0 .or. nBasisi == 0) cycle

    do jCnttp=iCnttp,nCnttp
      ! still figure out how to loop only over the centers belonging to the
      ! same fragment (keep track of mdc?) ! still to be done !!!
      if (.not. dbsc(jCnttp)%Frag) cycle

      do jAng=0,dbsc(jCnttp)%nVal-1
        jShll = dbsc(jCnttp)%iVal+jAng
        nExpj = Shells(jShll)%nExp
        nBasisj = Shells(jShll)%nBasis
        if (nExpj == 0 .or. nBasisj == 0) cycle

        ip = 2*maxDensSize
        nac = 4*(la+1)*(la+2)/2*(iAng+1)*(iAng+2)/2
        ip = ip+nExpi*nac
        ip = ip+3*nExpi
        ip = ip+nExpi
        ip = ip+nExpi
        ip = ip+nExpi
        nHer = ((la+1)+iAng+2)/2
        nOrder = max(nHer,nOrder)
        ip = ip+nExpi*3*nHer*(la+2)
        ip = ip+nExpi*3*nHer*(iAng+1)
        ip = ip+nExpi*3*nHer*(lr+1)
        ip = ip+nExpi*3*nHer*(la+2)*(iAng+1)*(lr+1)
        ip = ip+nExpi

        Mem = max(Mem,ip)
        ip = ip-nExpi*(6+3*nHer*((la+2)+(iAng+1)+(lr+1)+(la+2)*(iAng+1)*(lr+1))+1)

        ncb = 4*(jAng+1)*(jAng+2)/2*(lb+1)*(lb+2)/2
        ip = ip+nExpj*ncb
        ip = ip+3*nExpj
        ip = ip+nExpj
        ip = ip+nExpj
        ip = ip+nExpj
        nHer = ((lb+1)+jAng+2)/2
        nOrder = max(nHer,nOrder)
        ip = ip+nExpj*3*nHer*(lb+2)
        ip = ip+nExpj*3*nHer*(jAng+1)
        ip = ip+nExpj*3*nHer*(lr+1)
        ip = ip+nExpj*3*nHer*(lb+2)*(jAng+1)*(lr+1)
        ip = ip+nExpj

        Mem = max(Mem,ip)
        ip = ip-nExpj*(6+3*nHer*((lb+2)+(jAng+1)+(lr+1)+(lb+2)*(jAng+1)*(lr+1))+1)

        ip = ip+max(max(nExpi,nBasisj)*nac,ncb*nBasisj)
        Mem = max(Mem,ip)
      end do  !jAng

    end do  !jCnttp

  end do !iAng

end do ! iCnttp
nHer = nOrder

return

end subroutine FragPMmG
