!--------------------------------------------------------------------------------------------------!
!   CP2K: A general program to perform molecular dynamics simulations                              !
!   Copyright 2000-2025 CP2K developers group <https://cp2k.org>                                   !
!                                                                                                  !
!   SPDX-License-Identifier: GPL-2.0-or-later                                                      !
!--------------------------------------------------------------------------------------------------!

! **************************************************************************************************
!> \brief Calculate localized minimal basis and analyze wavefunctions
!> \par History
!>      12.2016 created [JGH]
!> \author JGH
! **************************************************************************************************
MODULE minbas_wfn_analysis
   USE atomic_charges,                  ONLY: print_atomic_charges,&
                                              print_bond_orders
   USE atomic_kind_types,               ONLY: atomic_kind_type
   USE bibliography,                    ONLY: Lu2004,&
                                              cite_reference
   USE cell_types,                      ONLY: cell_type
   USE cp_blacs_env,                    ONLY: cp_blacs_env_type
   USE cp_control_types,                ONLY: dft_control_type
   USE cp_dbcsr_api,                    ONLY: &
        dbcsr_copy, dbcsr_create, dbcsr_distribution_type, dbcsr_dot, dbcsr_get_block_p, &
        dbcsr_get_occupation, dbcsr_iterator_blocks_left, dbcsr_iterator_next_block, &
        dbcsr_iterator_start, dbcsr_iterator_stop, dbcsr_iterator_type, dbcsr_multiply, &
        dbcsr_p_type, dbcsr_release, dbcsr_set, dbcsr_type, dbcsr_type_no_symmetry, &
        dbcsr_type_symmetric
   USE cp_dbcsr_operations,             ONLY: copy_dbcsr_to_fm,&
                                              cp_dbcsr_plus_fm_fm_t,&
                                              cp_dbcsr_sm_fm_multiply,&
                                              dbcsr_allocate_matrix_set,&
                                              dbcsr_deallocate_matrix_set
   USE cp_fm_basic_linalg,              ONLY: cp_fm_column_scale
   USE cp_fm_struct,                    ONLY: cp_fm_struct_create,&
                                              cp_fm_struct_release,&
                                              cp_fm_struct_type
   USE cp_fm_types,                     ONLY: cp_fm_create,&
                                              cp_fm_get_diag,&
                                              cp_fm_release,&
                                              cp_fm_to_fm,&
                                              cp_fm_type
   USE cp_log_handling,                 ONLY: cp_get_default_logger,&
                                              cp_logger_type
   USE cp_output_handling,              ONLY: cp_print_key_finished_output,&
                                              cp_print_key_unit_nr
   USE cp_realspace_grid_cube,          ONLY: cp_pw_to_cube
   USE input_section_types,             ONLY: section_get_ivals,&
                                              section_vals_get,&
                                              section_vals_get_subs_vals,&
                                              section_vals_type,&
                                              section_vals_val_get
   USE iterate_matrix,                  ONLY: invert_Hotelling
   USE kinds,                           ONLY: default_path_length,&
                                              dp
   USE message_passing,                 ONLY: mp_para_env_type
   USE minbas_methods,                  ONLY: minbas_calculation
   USE molden_utils,                    ONLY: write_mos_molden
   USE mulliken,                        ONLY: compute_bond_order,&
                                              mulliken_charges
   USE parallel_gemm_api,               ONLY: parallel_gemm
   USE particle_list_types,             ONLY: particle_list_type
   USE particle_methods,                ONLY: get_particle_set
   USE particle_types,                  ONLY: particle_type
   USE pw_env_types,                    ONLY: pw_env_get,&
                                              pw_env_type
   USE pw_pool_types,                   ONLY: pw_pool_type
   USE pw_types,                        ONLY: pw_c1d_gs_type,&
                                              pw_r3d_rs_type
   USE qs_collocate_density,            ONLY: calculate_wavefunction
   USE qs_environment_types,            ONLY: get_qs_env,&
                                              qs_environment_type
   USE qs_kind_types,                   ONLY: qs_kind_type
   USE qs_ks_types,                     ONLY: get_ks_env,&
                                              qs_ks_env_type
   USE qs_mo_methods,                   ONLY: make_basis_lowdin
   USE qs_mo_types,                     ONLY: allocate_mo_set,&
                                              deallocate_mo_set,&
                                              get_mo_set,&
                                              mo_set_type,&
                                              set_mo_set
   USE qs_subsys_types,                 ONLY: qs_subsys_get,&
                                              qs_subsys_type
#include "./base/base_uses.f90"

   IMPLICIT NONE
   PRIVATE

   CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'minbas_wfn_analysis'

   PUBLIC ::  minbas_analysis

! **************************************************************************************************

CONTAINS

! **************************************************************************************************
!> \brief ...
!> \param qs_env ...
!> \param input_section ...
!> \param unit_nr ...
! **************************************************************************************************
   SUBROUTINE minbas_analysis(qs_env, input_section, unit_nr)
      TYPE(qs_environment_type), POINTER                 :: qs_env
      TYPE(section_vals_type), POINTER                   :: input_section
      INTEGER, INTENT(IN)                                :: unit_nr

      CHARACTER(len=*), PARAMETER                        :: routineN = 'minbas_analysis'

      INTEGER                                            :: handle, homo, i, ispin, nao, natom, &
                                                            nimages, nmao, nmo, nspin
      INTEGER, ALLOCATABLE, DIMENSION(:, :, :)           :: ecount
      INTEGER, DIMENSION(:), POINTER                     :: col_blk_sizes, row_blk_sizes
      LOGICAL                                            :: do_bondorder, explicit, full_ortho, occeq
      REAL(KIND=dp)                                      :: alpha, amax, eps_filter, filter_eps, &
                                                            trace
      REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :)        :: border, fnorm, mcharge, prmao
      REAL(KIND=dp), DIMENSION(:), POINTER               :: occupation_numbers
      TYPE(cp_blacs_env_type), POINTER                   :: blacs_env
      TYPE(cp_fm_struct_type), POINTER                   :: fm_struct_a, fm_struct_b, fm_struct_c
      TYPE(cp_fm_type)                                   :: fm1, fm2, fm3, fm4
      TYPE(cp_fm_type), POINTER                          :: fm_mos
      TYPE(dbcsr_distribution_type), POINTER             :: dbcsr_dist
      TYPE(dbcsr_p_type), DIMENSION(:), POINTER          :: mao_coef, pqmat, quambo, sqmat
      TYPE(dbcsr_p_type), DIMENSION(:, :), POINTER       :: matrix_s
      TYPE(dbcsr_type)                                   :: psmat, sinv, smao, smaox, spmat
      TYPE(dbcsr_type), POINTER                          :: smat
      TYPE(dft_control_type), POINTER                    :: dft_control
      TYPE(mo_set_type), ALLOCATABLE, DIMENSION(:)       :: mbas
      TYPE(mo_set_type), DIMENSION(:), POINTER           :: mos
      TYPE(mp_para_env_type), POINTER                    :: para_env
      TYPE(particle_type), DIMENSION(:), POINTER         :: particle_set
      TYPE(qs_kind_type), DIMENSION(:), POINTER          :: qs_kind_set
      TYPE(qs_ks_env_type), POINTER                      :: ks_env
      TYPE(section_vals_type), POINTER                   :: molden_section

      ! only do MINBAS analysis if explicitly requested
      CALL section_vals_get(input_section, explicit=explicit)
      IF (.NOT. explicit) RETURN

      ! k-points?
      CALL get_qs_env(qs_env, dft_control=dft_control)
      nspin = dft_control%nspins
      nimages = dft_control%nimages
      IF (nimages > 1) THEN
         IF (unit_nr > 0) THEN
            WRITE (UNIT=unit_nr, FMT="(T2,A)") &
               "K-Points: Localized Minimal Basis Analysis not available."
         END IF
      END IF
      IF (nimages > 1) RETURN

      CALL timeset(routineN, handle)

      IF (unit_nr > 0) THEN
         WRITE (unit_nr, '(/,T2,A)') '!-----------------------------------------------------------------------------!'
         WRITE (UNIT=unit_nr, FMT="(T26,A)") "LOCALIZED MINIMAL BASIS ANALYSIS"
         WRITE (UNIT=unit_nr, FMT="(T18,A)") "W.C. Lu et al, J. Chem. Phys. 120, 2629 (2004)"
         WRITE (unit_nr, '(T2,A)') '!-----------------------------------------------------------------------------!'
      END IF
      CALL cite_reference(Lu2004)

      ! input options
      CALL section_vals_val_get(input_section, "EPS_FILTER", r_val=eps_filter)
      CALL section_vals_val_get(input_section, "FULL_ORTHOGONALIZATION", l_val=full_ortho)
      CALL section_vals_val_get(input_section, "BOND_ORDER", l_val=do_bondorder)

      ! generate MAOs and QUAMBOs
      CALL get_qs_env(qs_env, mos=mos)
      NULLIFY (quambo, mao_coef)
      CALL minbas_calculation(qs_env, mos, quambo, mao=mao_coef, iounit=unit_nr, &
                              full_ortho=full_ortho, eps_filter=eps_filter)
      IF (ASSOCIATED(quambo)) THEN
         CALL get_mo_set(mo_set=mos(1), nao=nao, nmo=nmo)
         CALL get_qs_env(qs_env=qs_env, ks_env=ks_env)
         CALL get_qs_env(qs_env=qs_env, qs_kind_set=qs_kind_set, natom=natom)
         CALL get_ks_env(ks_env=ks_env, particle_set=particle_set, dbcsr_dist=dbcsr_dist)
         ALLOCATE (row_blk_sizes(natom), col_blk_sizes(natom))
         CALL get_particle_set(particle_set, qs_kind_set, nsgf=row_blk_sizes)
         CALL get_particle_set(particle_set, qs_kind_set, nmao=col_blk_sizes)
         nmao = SUM(col_blk_sizes)

         NULLIFY (pqmat, sqmat)
         CALL dbcsr_allocate_matrix_set(sqmat, nspin)
         CALL dbcsr_allocate_matrix_set(pqmat, nspin)
         DO ispin = 1, nspin
            ALLOCATE (sqmat(ispin)%matrix)
            CALL dbcsr_create(matrix=sqmat(ispin)%matrix, &
                              name="SQMAT", dist=dbcsr_dist, matrix_type=dbcsr_type_symmetric, &
                              row_blk_size=col_blk_sizes, col_blk_size=col_blk_sizes, nze=0)
            ALLOCATE (pqmat(ispin)%matrix)
            CALL dbcsr_create(matrix=pqmat(ispin)%matrix, &
                              name="PQMAT", dist=dbcsr_dist, matrix_type=dbcsr_type_symmetric, &
                              row_blk_size=col_blk_sizes, col_blk_size=col_blk_sizes, nze=0)
         END DO
         DEALLOCATE (row_blk_sizes, col_blk_sizes)

         ! Start wfn analysis
         IF (unit_nr > 0) THEN
            WRITE (unit_nr, '(/,T2,A)') 'Localized Minimal Basis Wavefunction Analysis'
         END IF

         ! localization of basis
         DO ispin = 1, nspin
            amax = dbcsr_get_occupation(quambo(ispin)%matrix)
            IF (unit_nr > 0) THEN
               WRITE (unit_nr, '(/,T2,A,I2,T69,F10.3,A2,/)') &
                  'Occupation of Basis Function Representation (Spin) ', ispin, amax*100._dp, ' %'
            END IF
         END DO

         CALL get_qs_env(qs_env, matrix_s_kp=matrix_s)
         CALL get_qs_env(qs_env=qs_env, para_env=para_env, blacs_env=blacs_env)
         CALL cp_fm_struct_create(fm_struct_a, nrow_global=nao, ncol_global=nmao, &
                                  para_env=para_env, context=blacs_env)
         CALL cp_fm_create(fm1, fm_struct_a)
         CALL cp_fm_struct_create(fm_struct_b, nrow_global=nmao, ncol_global=nmo, &
                                  para_env=para_env, context=blacs_env)
         CALL cp_fm_create(fm2, fm_struct_b)
         CALL cp_fm_create(fm3, fm_struct_b)
         CALL cp_fm_struct_create(fm_struct_c, nrow_global=nmo, ncol_global=nmo, &
                                  para_env=para_env, context=blacs_env)
         CALL cp_fm_create(fm4, fm_struct_c)
         ALLOCATE (fnorm(nmo, nspin), ecount(natom, 3, nspin), prmao(natom, nspin))
         ecount = 0
         prmao = 0.0_dp
         DO ispin = 1, nspin
            CALL dbcsr_create(smao, name="S*QM", template=mao_coef(1)%matrix)
            smat => matrix_s(1, 1)%matrix
            CALL dbcsr_multiply("N", "N", 1.0_dp, smat, quambo(ispin)%matrix, 0.0_dp, smao)
            ! calculate atomic extend of basis
            CALL pm_extend(quambo(ispin)%matrix, smao, ecount(:, :, ispin))
            CALL dbcsr_create(sinv, name="QM*S*QM", template=sqmat(ispin)%matrix)
            CALL dbcsr_multiply("T", "N", 1.0_dp, quambo(ispin)%matrix, smao, 0.0_dp, sqmat(ispin)%matrix)
            ! atomic MAO projection
            CALL project_mao(mao_coef(ispin)%matrix, smao, sqmat(ispin)%matrix, prmao(:, ispin))
            ! invert overlap
            CALL invert_Hotelling(sinv, sqmat(ispin)%matrix, 1.e-6_dp, silent=.TRUE.)
            CALL dbcsr_create(smaox, name="S*QM*SINV", template=smao)
            CALL dbcsr_multiply("N", "N", 1.0_dp, smao, sinv, 0.0_dp, smaox)
            CALL copy_dbcsr_to_fm(smaox, fm1)
            CALL get_mo_set(mos(ispin), mo_coeff=fm_mos, homo=homo)
            CALL parallel_gemm("T", "N", nmao, nmo, nao, 1.0_dp, fm1, fm_mos, 0.0_dp, fm2)
            CALL cp_dbcsr_sm_fm_multiply(sqmat(ispin)%matrix, fm2, fm3, nmo)
            CALL parallel_gemm("T", "N", nmo, nmo, nmao, 1.0_dp, fm2, fm3, 0.0_dp, fm4)
            CALL cp_fm_get_diag(fm4, fnorm(1:nmo, ispin))
            ! fm2 are the projected MOs (in MAO basis); orthogonalize the occupied subspace
            CALL make_basis_lowdin(vmatrix=fm2, ncol=homo, matrix_s=sqmat(ispin)%matrix)
            ! pmat
            CALL get_mo_set(mos(ispin), occupation_numbers=occupation_numbers, maxocc=alpha)
            occeq = ALL(occupation_numbers(1:homo) == alpha)
            CALL dbcsr_copy(pqmat(ispin)%matrix, sqmat(ispin)%matrix)
            CALL dbcsr_set(pqmat(ispin)%matrix, 0.0_dp)
            IF (occeq) THEN
               CALL cp_dbcsr_plus_fm_fm_t(sparse_matrix=pqmat(ispin)%matrix, matrix_v=fm2, &
                                          ncol=homo, alpha=alpha, keep_sparsity=.FALSE.)
            ELSE
               CALL cp_fm_to_fm(fm2, fm3)
               CALL cp_fm_column_scale(fm3, occupation_numbers(1:homo))
               alpha = 1.0_dp
               CALL cp_dbcsr_plus_fm_fm_t(sparse_matrix=pqmat(ispin)%matrix, matrix_v=fm2, &
                                          matrix_g=fm3, ncol=homo, alpha=alpha, keep_sparsity=.TRUE.)
            END IF

            CALL dbcsr_release(smao)
            CALL dbcsr_release(smaox)
            CALL dbcsr_release(sinv)
         END DO
         ! Basis extension
         CALL para_env%sum(ecount)
         IF (unit_nr > 0) THEN
            IF (nspin == 1) THEN
               WRITE (unit_nr, '(T2,A,T20,A,T40,A,T60,A)') 'Ref. Atom', ' # > 0.100 ', ' # > 0.010 ', ' # > 0.001 '
               DO i = 1, natom
                  WRITE (unit_nr, '(T2,I8,T20,I10,T40,I10,T60,I10)') i, ecount(i, 1:3, 1)
               END DO
            ELSE
               WRITE (unit_nr, '(T2,A,T20,A,T40,A,T60,A)') 'Ref. Atom', ' # > 0.100 ', ' # > 0.010 ', ' # > 0.001 '
               DO i = 1, natom
                  WRITE (unit_nr, '(T2,I8,T20,2I6,T40,2I6,T60,2I6)') &
                     i, ecount(i, 1, 1:2), ecount(i, 2, 1:2), ecount(i, 3, 1:2)
               END DO
            END IF
         END IF
         ! MAO projection
         CALL para_env%sum(prmao)
         IF (unit_nr > 0) THEN
            DO ispin = 1, nspin
               WRITE (unit_nr, '(/,T2,A,I2)') 'Projection on same atom MAO orbitals: Spin ', ispin
               DO i = 1, natom, 2
                  IF (i < natom) THEN
                     WRITE (unit_nr, '(T2,A,I8,T20,A,F10.6,T42,A,I8,T60,A,F10.6)') &
                        " Atom:", i, "Projection:", prmao(i, ispin), " Atom:", i + 1, "Projection:", prmao(i + 1, ispin)
                  ELSE
                     WRITE (unit_nr, '(T2,A,I8,T20,A,F10.6)') " Atom:", i, "Projection:", prmao(i, ispin)
                  END IF
               END DO
            END DO
         END IF
         ! MO expansion completness
         DO ispin = 1, nspin
            CALL get_mo_set(mos(ispin), homo=homo, nmo=nmo)
            IF (unit_nr > 0) THEN
               WRITE (unit_nr, '(/,T2,A,I2)') 'MO expansion in Localized Minimal Basis: Spin ', ispin
               WRITE (unit_nr, '(T64,A)') 'Occupied Orbitals'
               WRITE (unit_nr, '(8F10.6)') fnorm(1:homo, ispin)
               WRITE (unit_nr, '(T65,A)') 'Virtual Orbitals'
               WRITE (unit_nr, '(8F10.6)') fnorm(homo + 1:nmo, ispin)
            END IF
         END DO
         ! Mulliken population
         IF (unit_nr > 0) THEN
            WRITE (unit_nr, '(/,T2,A)') 'Mulliken Population Analysis '
         END IF
         ALLOCATE (mcharge(natom, nspin))
         DO ispin = 1, nspin
            CALL dbcsr_dot(pqmat(ispin)%matrix, sqmat(ispin)%matrix, trace)
            IF (unit_nr > 0) THEN
               WRITE (unit_nr, '(T2,A,I2,T66,F15.4)') 'Number of Electrons: Trace(PS) Spin ', ispin, trace
            END IF
            CALL mulliken_charges(pqmat(ispin)%matrix, sqmat(ispin)%matrix, para_env, mcharge(:, ispin))
         END DO
         CALL print_atomic_charges(particle_set, qs_kind_set, unit_nr, "Minimal Basis Mulliken Charges", &
                                   electronic_charges=mcharge)
         ! Mayer bond orders
         IF (do_bondorder) THEN
            ALLOCATE (border(natom, natom))
            border = 0.0_dp
            CALL dbcsr_create(psmat, name="PS", template=sqmat(1)%matrix, matrix_type=dbcsr_type_no_symmetry)
            CALL dbcsr_create(spmat, name="SP", template=sqmat(1)%matrix, matrix_type=dbcsr_type_no_symmetry)
            filter_eps = 1.e-6_dp
            DO ispin = 1, nspin
               CALL dbcsr_multiply("N", "N", 1.0_dp, pqmat(ispin)%matrix, sqmat(ispin)%matrix, 0.0_dp, psmat, &
                                   filter_eps=filter_eps)
               CALL dbcsr_multiply("N", "N", 1.0_dp, sqmat(ispin)%matrix, pqmat(ispin)%matrix, 0.0_dp, spmat, &
                                   filter_eps=filter_eps)
               CALL compute_bond_order(psmat, spmat, border)
            END DO
            CALL para_env%sum(border)
            border = border*REAL(nspin, KIND=dp)
            CALL dbcsr_release(psmat)
            CALL dbcsr_release(spmat)
            CALL print_bond_orders(particle_set, unit_nr, border)
            DEALLOCATE (border)
         END IF

         ! for printing purposes we now copy the QUAMBOs into MO format
         ALLOCATE (mbas(nspin))
         DO ispin = 1, nspin
            CALL allocate_mo_set(mbas(ispin), nao, nmao, nmao, 0.0_dp, 1.0_dp, 0.0_dp)
            CALL set_mo_set(mbas(ispin), homo=nmao)
            ALLOCATE (mbas(ispin)%eigenvalues(nmao))
            mbas(ispin)%eigenvalues = 0.0_dp
            ALLOCATE (mbas(ispin)%occupation_numbers(nmao))
            mbas(ispin)%occupation_numbers = 1.0_dp
            CALL cp_fm_create(mbas(ispin)%mo_coeff, fm_struct_a)
            CALL copy_dbcsr_to_fm(quambo(ispin)%matrix, mbas(ispin)%mo_coeff)
         END DO

         ! Print basis functions: cube files
         DO ispin = 1, nspin
            CALL get_mo_set(mbas(ispin), mo_coeff=fm_mos)
            CALL post_minbas_cubes(qs_env, input_section, fm_mos, ispin)
         END DO
         ! Print basis functions: molden format
         molden_section => section_vals_get_subs_vals(input_section, "MINBAS_MOLDEN")
         CALL write_mos_molden(mbas, qs_kind_set, particle_set, molden_section)
         DO ispin = 1, nspin
            CALL deallocate_mo_set(mbas(ispin))
         END DO
         DEALLOCATE (mbas)

         DEALLOCATE (fnorm, ecount, prmao, mcharge)
         CALL cp_fm_release(fm1)
         CALL cp_fm_release(fm2)
         CALL cp_fm_release(fm3)
         CALL cp_fm_release(fm4)
         CALL cp_fm_struct_release(fm_struct_a)
         CALL cp_fm_struct_release(fm_struct_b)
         CALL cp_fm_struct_release(fm_struct_c)

         ! clean up
         CALL dbcsr_deallocate_matrix_set(sqmat)
         CALL dbcsr_deallocate_matrix_set(pqmat)
         CALL dbcsr_deallocate_matrix_set(mao_coef)
         CALL dbcsr_deallocate_matrix_set(quambo)

      END IF

      IF (unit_nr > 0) THEN
         WRITE (unit_nr, '(/,T2,A)') &
            '!--------------------------END OF MINBAS ANALYSIS-----------------------------!'
      END IF

      CALL timestop(handle)

   END SUBROUTINE minbas_analysis

! **************************************************************************************************
!> \brief ...
!> \param quambo ...
!> \param smao ...
!> \param ecount ...
! **************************************************************************************************
   SUBROUTINE pm_extend(quambo, smao, ecount)
      TYPE(dbcsr_type)                                   :: quambo, smao
      INTEGER, DIMENSION(:, :), INTENT(INOUT)            :: ecount

      INTEGER                                            :: iatom, jatom, n
      LOGICAL                                            :: found
      REAL(KIND=dp)                                      :: wij
      REAL(KIND=dp), DIMENSION(:, :), POINTER            :: qblock, sblock
      TYPE(dbcsr_iterator_type)                          :: dbcsr_iter

      CALL dbcsr_iterator_start(dbcsr_iter, quambo)
      DO WHILE (dbcsr_iterator_blocks_left(dbcsr_iter))
         CALL dbcsr_iterator_next_block(dbcsr_iter, iatom, jatom, qblock)
         CALL dbcsr_get_block_p(matrix=smao, row=iatom, col=jatom, BLOCK=sblock, found=found)
         IF (found) THEN
            n = SIZE(qblock, 2)
            wij = ABS(SUM(qblock*sblock))/REAL(n, KIND=dp)
            IF (wij > 0.1_dp) THEN
               ecount(jatom, 1) = ecount(jatom, 1) + 1
            ELSEIF (wij > 0.01_dp) THEN
               ecount(jatom, 2) = ecount(jatom, 2) + 1
            ELSEIF (wij > 0.001_dp) THEN
               ecount(jatom, 3) = ecount(jatom, 3) + 1
            END IF
         END IF
      END DO
      CALL dbcsr_iterator_stop(dbcsr_iter)

   END SUBROUTINE pm_extend

! **************************************************************************************************
!> \brief ...
!> \param mao ...
!> \param smao ...
!> \param sovl ...
!> \param prmao ...
! **************************************************************************************************
   SUBROUTINE project_mao(mao, smao, sovl, prmao)
      TYPE(dbcsr_type)                                   :: mao, smao, sovl
      REAL(KIND=dp), DIMENSION(:), INTENT(INOUT)         :: prmao

      INTEGER                                            :: i, iatom, jatom, n
      LOGICAL                                            :: found
      REAL(KIND=dp)                                      :: wi
      REAL(KIND=dp), DIMENSION(:, :), POINTER            :: qblock, sblock, so
      TYPE(dbcsr_iterator_type)                          :: dbcsr_iter

      CALL dbcsr_iterator_start(dbcsr_iter, mao)
      DO WHILE (dbcsr_iterator_blocks_left(dbcsr_iter))
         CALL dbcsr_iterator_next_block(dbcsr_iter, iatom, jatom, qblock)
         CPASSERT(iatom == jatom)
         CALL dbcsr_get_block_p(matrix=smao, row=iatom, col=jatom, BLOCK=sblock, found=found)
         IF (found) THEN
            CALL dbcsr_get_block_p(matrix=sovl, row=iatom, col=jatom, BLOCK=so, found=found)
            n = SIZE(qblock, 2)
            DO i = 1, n
               wi = SUM(qblock(:, i)*sblock(:, i))
               prmao(iatom) = prmao(iatom) + wi/so(i, i)
            END DO
         END IF
      END DO
      CALL dbcsr_iterator_stop(dbcsr_iter)

   END SUBROUTINE project_mao

! **************************************************************************************************
!> \brief Computes and prints the Cube Files for the minimal basis set
!> \param qs_env ...
!> \param print_section ...
!> \param minbas_coeff ...
!> \param ispin ...
! **************************************************************************************************
   SUBROUTINE post_minbas_cubes(qs_env, print_section, minbas_coeff, ispin)
      TYPE(qs_environment_type), POINTER                 :: qs_env
      TYPE(section_vals_type), POINTER                   :: print_section
      TYPE(cp_fm_type), INTENT(IN)                       :: minbas_coeff
      INTEGER, INTENT(IN)                                :: ispin

      CHARACTER(LEN=default_path_length)                 :: filename, title
      INTEGER                                            :: i, i_rep, ivec, iw, j, n_rep, natom
      INTEGER, DIMENSION(:), POINTER                     :: blk_sizes, first_bas, ilist, stride
      LOGICAL                                            :: explicit, mpi_io
      TYPE(atomic_kind_type), DIMENSION(:), POINTER      :: atomic_kind_set
      TYPE(cell_type), POINTER                           :: cell
      TYPE(cp_logger_type), POINTER                      :: logger
      TYPE(dft_control_type), POINTER                    :: dft_control
      TYPE(particle_list_type), POINTER                  :: particles
      TYPE(particle_type), DIMENSION(:), POINTER         :: particle_set
      TYPE(pw_c1d_gs_type)                               :: wf_g
      TYPE(pw_env_type), POINTER                         :: pw_env
      TYPE(pw_pool_type), POINTER                        :: auxbas_pw_pool
      TYPE(pw_r3d_rs_type)                               :: wf_r
      TYPE(qs_kind_type), DIMENSION(:), POINTER          :: qs_kind_set
      TYPE(qs_subsys_type), POINTER                      :: subsys
      TYPE(section_vals_type), POINTER                   :: minbas_section

      minbas_section => section_vals_get_subs_vals(print_section, "MINBAS_CUBE")
      CALL section_vals_get(minbas_section, explicit=explicit)
      IF (.NOT. explicit) RETURN

      logger => cp_get_default_logger()
      stride => section_get_ivals(print_section, "MINBAS_CUBE%STRIDE")

      CALL get_qs_env(qs_env=qs_env, atomic_kind_set=atomic_kind_set, qs_kind_set=qs_kind_set, &
                      subsys=subsys, cell=cell, particle_set=particle_set, pw_env=pw_env, dft_control=dft_control)
      CALL qs_subsys_get(subsys, particles=particles)

      CALL get_qs_env(qs_env=qs_env, natom=natom)
      ALLOCATE (blk_sizes(natom), first_bas(0:natom))
      CALL get_particle_set(particle_set, qs_kind_set, nmao=blk_sizes)
      first_bas(0) = 0
      DO i = 1, natom
         first_bas(i) = first_bas(i - 1) + blk_sizes(i)
      END DO

      CALL pw_env_get(pw_env, auxbas_pw_pool=auxbas_pw_pool)
      CALL auxbas_pw_pool%create_pw(wf_r)
      CALL auxbas_pw_pool%create_pw(wf_g)

      ! loop over list of atoms
      CALL section_vals_val_get(minbas_section, "ATOM_LIST", n_rep_val=n_rep)
      IF (n_rep == 0) THEN
         DO i = 1, natom
            DO ivec = first_bas(i - 1) + 1, first_bas(i)
               WRITE (filename, '(a4,I5.5,a1,I1.1)') "MINBAS_", ivec, "_", ispin
               WRITE (title, *) "MINIMAL BASIS ", ivec, " atom ", i, " spin ", ispin
               mpi_io = .TRUE.
               iw = cp_print_key_unit_nr(logger, print_section, "MINBAS_CUBE", extension=".cube", &
                                         middle_name=TRIM(filename), file_position="REWIND", log_filename=.FALSE., &
                                         mpi_io=mpi_io)
               CALL calculate_wavefunction(minbas_coeff, ivec, wf_r, wf_g, atomic_kind_set, qs_kind_set, &
                                           cell, dft_control, particle_set, pw_env)
               CALL cp_pw_to_cube(wf_r, iw, title, particles=particles, stride=stride, mpi_io=mpi_io)
               CALL cp_print_key_finished_output(iw, logger, print_section, "MINBAS_CUBE", mpi_io=mpi_io)
            END DO
         END DO
      ELSE
         DO i_rep = 1, n_rep
            CALL section_vals_val_get(minbas_section, "ATOM_LIST", i_rep_val=i_rep, i_vals=ilist)
            DO i = 1, SIZE(ilist, 1)
               j = ilist(i)
               DO ivec = first_bas(j - 1) + 1, first_bas(j)
                  WRITE (filename, '(a4,I5.5,a1,I1.1)') "MINBAS_", ivec, "_", ispin
                  WRITE (title, *) "MINIMAL BASIS ", ivec, " atom ", j, " spin ", ispin
                  mpi_io = .TRUE.
                  iw = cp_print_key_unit_nr(logger, print_section, "MINBAS_CUBE", extension=".cube", &
                                            middle_name=TRIM(filename), file_position="REWIND", log_filename=.FALSE., &
                                            mpi_io=mpi_io)
                  CALL calculate_wavefunction(minbas_coeff, ivec, wf_r, wf_g, atomic_kind_set, qs_kind_set, &
                                              cell, dft_control, particle_set, pw_env)
                  CALL cp_pw_to_cube(wf_r, iw, title, particles=particles, stride=stride, mpi_io=mpi_io)
                  CALL cp_print_key_finished_output(iw, logger, print_section, "MINBAS_CUBE", mpi_io=mpi_io)
               END DO
            END DO
         END DO
      END IF
      DEALLOCATE (blk_sizes, first_bas)
      CALL auxbas_pw_pool%give_back_pw(wf_r)
      CALL auxbas_pw_pool%give_back_pw(wf_g)

   END SUBROUTINE post_minbas_cubes

END MODULE minbas_wfn_analysis
