add maximum overlap method in hartree fock

src/scf_utils/EZFIO.cfg

@@ -45,6 +45,12 @@ type: double precision
 doc: Calculated HF energy
 interface: ezfio
 
+[do_mom]
+type: logical
+doc: If true, this will run a MOM calculation. The overlap will be computed at each step with respect to the initial MOs. After an initial Hartree-Fock calculation, the guess can be created by swapping molecular orbitals through the qp run swap_mos command. 
+interface: ezfio,provider,ocaml
+default: False
+
 [frozen_orb_scf]
 type: logical
 doc: If true, leave untouched all the orbitals defined as core and optimize all the orbitals defined as active with qp_set_mo_class

src/scf_utils/reorder_mo_max_overlap.irp.f

@@ -0,0 +1,88 @@
+ subroutine reorder_mo_max_overlap
+  implicit none
+   BEGIN_DOC
+   ! routines that compute the projection of each MO of the current `mo_coef` on the space spanned by the occupied orbitals of `mo_coef_begin_iteration`
+   END_DOC
+   integer :: i,j,k,l
+   double precision, allocatable :: overlap(:,:)
+   double precision, allocatable :: proj(:)
+   integer, allocatable :: iorder(:)
+   double precision, allocatable :: mo_coef_tmp(:,:)
+   allocate(overlap(mo_num,mo_num),proj(mo_num),iorder(mo_num),mo_coef_tmp(ao_num,mo_num))
+   
+   overlap(:,:) = 0d0
+   mo_coef_tmp(:,:) = 0d0
+   proj(:) = 0d0
+   iorder(:) = 0d0
+   
+   ! this loop compute the overlap between the initial and the current MOS
+   do i = 1, mo_num ! old mo
+      do j = 1, mo_num ! curent mo
+         do k = 1, ao_num
+            do l = 1, ao_num
+               overlap(i,j) += mo_coef_begin_iteration(k,i)* ao_overlap(k,l) * mo_coef(l,j) 
+            enddo
+         enddo
+      enddo
+   enddo
+
+   ! for each orbital compute the best overlap
+   
+   do i = 1, mo_num
+      iorder(i) = i ! initialize the iorder list as we need it to sort later
+      do j = 1, elec_alpha_num
+         proj(i) += overlap(j,i)*overlap(j,i) ! compute the projection of current orbital i on the occupied space of the initial orbitals
+      enddo
+      proj(i) = dsqrt(proj(i))
+   enddo
+   ! sort the list of projection to find the mos with the largest overlap
+   call dsort(proj(:),iorder(:),mo_num)
+   ! reorder orbitals according to projection
+   do i=1,mo_num
+      mo_coef_tmp(:,i) = mo_coef(:,iorder(mo_num+1-i)) 
+   enddo
+
+   ! update the orbitals
+   mo_coef(:,:) =  mo_coef_tmp(:,:)
+   
+   ! if the determinant is open-shell we need to make sure that the singly occupied orbital correspond to the initial ones
+   if (elec_alpha_num > elec_beta_num) then
+      double precision, allocatable :: overlap_alpha(:,:)
+      double precision, allocatable :: proj_alpha(:)
+      integer, allocatable :: iorder_alpha(:)
+      allocate(overlap_alpha(mo_num,elec_alpha_num),proj_alpha(elec_alpha_num),iorder_alpha(elec_alpha_num))
+      overlap_alpha(:,:) = 0d0
+      proj_alpha(:) = 0d0
+      iorder_alpha(:) = 0d0
+      do i = 1, mo_num ! old mo
+         do j = 1, elec_alpha_num ! curent mo
+            do k = 1, ao_num
+               do l = 1, ao_num
+                  overlap_alpha(i,j) += mo_coef_begin_iteration(k,i) * ao_overlap(k,l) * mo_coef(l,j) 
+               enddo
+            enddo
+         enddo
+      enddo
+      do i = 1, elec_alpha_num
+         iorder_alpha(i) = i ! initialize the iorder list as we need it to sort later
+         do j = 1, elec_beta_num
+            proj_alpha(i) += overlap_alpha(j,i)*overlap_alpha(j,i) ! compute the projection of current orbital i on the beta occupied space of the initial orbitals
+         enddo
+         proj_alpha(i) = dsqrt(proj_alpha(i))
+      enddo
+      ! sort the list of projection to find the mos with the largest overlap
+      call dsort(proj_alpha(:),iorder_alpha(:),elec_alpha_num)
+      ! reorder orbitals according to projection
+      do i=1,elec_alpha_num
+         mo_coef_tmp(:,i) = mo_coef(:,iorder_alpha(elec_alpha_num+1-i)) 
+      enddo
+      do i=1,elec_alpha_num
+         mo_coef(:,i) = mo_coef_tmp(:,i) 
+      enddo
+   endif
+   
+   deallocate(overlap, proj, iorder, mo_coef_tmp)
+
+  
+ end
+

src/scf_utils/roothaan_hall_scf.irp.f

@@ -51,6 +51,11 @@ END_DOC
 !
   PROVIDE FPS_SPF_matrix_AO Fock_matrix_AO 
 
+  ! Initialize MO to run IMOM
+  if(do_mom)then
+     call initialize_mo_coef_begin_iteration
+  endif
+  
   converged = .False.
   do while ( .not.converged .and. (iteration_SCF < n_it_SCF_max) )
 
@@ -89,15 +94,16 @@ END_DOC
       TOUCH Fock_matrix_AO_alpha Fock_matrix_AO_beta
 
    endif
-
     MO_coef = eigenvectors_Fock_matrix_MO
+    if(do_mom)then
+       call reorder_mo_max_overlap
+    endif
     if(frozen_orb_scf)then
      call reorder_core_orb
      call initialize_mo_coef_begin_iteration
     endif
 
     TOUCH MO_coef
-
 !   Calculate error vectors
 
     max_error_DIIS = maxval(Abs(FPS_SPF_Matrix_MO))
@@ -106,13 +112,14 @@ END_DOC
 
     energy_SCF = SCF_energy
     Delta_Energy_SCF = energy_SCF - energy_SCF_previous
-    if ( (SCF_algorithm == 'DIIS').and.(Delta_Energy_SCF > 0.d0) ) then
+    ! if ( (SCF_algorithm == 'DIIS').and.(Delta_Energy_SCF > 0.d0) ) then
-      Fock_matrix_AO(1:ao_num,1:ao_num) = Fock_matrix_DIIS (1:ao_num,1:ao_num,index_dim_DIIS)
+    !   Fock_matrix_AO(1:ao_num,1:ao_num) = Fock_matrix_DIIS (1:ao_num,1:ao_num,index_dim_DIIS)
-      Fock_matrix_AO_alpha = Fock_matrix_AO*0.5d0
+    !   Fock_matrix_AO_alpha = Fock_matrix_AO*0.5d0
-      Fock_matrix_AO_beta  = Fock_matrix_AO*0.5d0
+    !   Fock_matrix_AO_beta  = Fock_matrix_AO*0.5d0
-      TOUCH Fock_matrix_AO_alpha Fock_matrix_AO_beta
+    !   TOUCH Fock_matrix_AO_alpha Fock_matrix_AO_beta
-    endif
+    ! endif
 
+    if (.not.do_mom) then
        double precision :: level_shift_save
        level_shift_save = level_shift
        mo_coef_save(1:ao_num,1:mo_num) = mo_coef(1:ao_num,1:mo_num)
@@ -125,6 +132,9 @@ END_DOC
           endif
           TOUCH mo_coef level_shift
           mo_coef(1:ao_num,1:mo_num) = eigenvectors_Fock_matrix_MO(1:ao_num,1:mo_num)
+          if(do_mom)then
+             call reorder_mo_max_overlap
+          endif
           if(frozen_orb_scf)then
              call reorder_core_orb
              call initialize_mo_coef_begin_iteration
@@ -141,6 +151,7 @@ END_DOC
        enddo
        level_shift = level_shift * 0.5d0
        SOFT_TOUCH level_shift
+    endif
     energy_SCF_previous = energy_SCF
 
     converged = ( (max_error_DIIS <= threshold_DIIS_nonzero) .and. &
@@ -228,6 +239,9 @@ END_DOC
     i = j+1
   enddo
 
+  if(do_mom)then
+     call reorder_mo_max_overlap
+  endif
 
   call save_mos