diff --git a/src/determinants/slater_rules.irp.f b/src/determinants/slater_rules.irp.f
index ee331295..0ce55109 100644
--- a/src/determinants/slater_rules.irp.f
+++ b/src/determinants/slater_rules.irp.f
@@ -2644,11 +2644,6 @@ end
 
 
 subroutine i_H_psi_complex(key,keys,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array)
-  !todo: modify/implement for complex
-  if (is_complex) then
-    print*,irp_here,' not implemented for complex'
-    stop -1
-  endif
   use bitmasks
   implicit none
   BEGIN_DOC
@@ -2662,13 +2657,13 @@ subroutine i_H_psi_complex(key,keys,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array
   integer, intent(in)            :: Nint, Ndet,Ndet_max,Nstate
   integer(bit_kind), intent(in)  :: keys(Nint,2,Ndet)
   integer(bit_kind), intent(in)  :: key(Nint,2)
-  double precision, intent(in)   :: coef(Ndet_max,Nstate)
-  double precision, intent(out)  :: i_H_psi_array(Nstate)
+  complex*16, intent(in)   :: coef(Ndet_max,Nstate)
+  complex*16, intent(out)  :: i_H_psi_array(Nstate)
 
   integer                        :: i, ii,j
   double precision               :: phase
   integer                        :: exc(0:2,2,2)
-  double precision               :: hij
+  complex*16               :: hij
   integer, allocatable           :: idx(:)
 
   ASSERT (Nint > 0)
@@ -2678,15 +2673,15 @@ subroutine i_H_psi_complex(key,keys,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array
   ASSERT (Ndet_max >= Ndet)
   allocate(idx(0:Ndet))
 
-  i_H_psi_array = 0.d0
+  i_H_psi_array = (0.d0,0.d0)
 
-  call filter_connected_i_H_psi0(keys,key,Nint,Ndet,idx)
+  call filter_connected_i_h_psi0(keys,key,Nint,Ndet,idx)
   if (Nstate == 1) then
 
     do ii=1,idx(0)
       i = idx(ii)
       !DIR$ FORCEINLINE
-      call i_H_j(keys(1,1,i),key,Nint,hij)
+      call i_h_j_complex(key,keys(1,1,i),Nint,hij)
       i_H_psi_array(1) = i_H_psi_array(1) + coef(i,1)*hij
     enddo
 
@@ -2695,7 +2690,7 @@ subroutine i_H_psi_complex(key,keys,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array
     do ii=1,idx(0)
       i = idx(ii)
       !DIR$ FORCEINLINE
-      call i_H_j(keys(1,1,i),key,Nint,hij)
+      call i_h_j_complex(key,keys(1,1,i),Nint,hij)
       do j = 1, Nstate
         i_H_psi_array(j) = i_H_psi_array(j) + coef(i,j)*hij
       enddo