diff --git a/plugins/Perturbation/pt2_new.irp.f b/plugins/Perturbation/pt2_new.irp.f
new file mode 100644
index 00000000..a991e483
--- /dev/null
+++ b/plugins/Perturbation/pt2_new.irp.f
@@ -0,0 +1,71 @@
+subroutine i_H_psi_pert_new_minilist(key,keys,idx_key,N_minilist,coef,Nint,Ndet,Ndet_max,Nstate,i_H_psi_array,coef_pert)
+  use bitmasks
+  implicit none
+  integer, intent(in)            :: Nint, Ndet,Ndet_max,Nstate,idx_key(Ndet), N_minilist
+  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)
+  double precision, intent(out)  :: coef_pert
+
+  integer                        :: idx(0:Ndet)
+  
+  integer                        :: i, ii,j, i_in_key, i_in_coef
+  double precision               :: phase
+  integer                        :: exc(0:2,2,2)
+  double precision               :: hij
+  double precision :: delta_e_final
+  double precision :: hjj
+  BEGIN_DOC
+! Computes <i|H|Psi> = \sum_J c_J <i|H|J>.
+!
+! Uses filter_connected_i_H_psi0 to get all the |J> to which |i>
+! is connected. The |J> are searched in short pre-computed lists.
+  END_DOC
+  
+  ASSERT (Nint > 0)
+  ASSERT (N_int == Nint)
+  ASSERT (Nstate > 0)
+  ASSERT (Ndet > 0)
+  ASSERT (Ndet_max >= Ndet)
+  i_H_psi_array = 0.d0
+  coef_pert = 0.d0
+  
+  call filter_connected_i_H_psi0(keys,key,Nint,N_minilist,idx)
+  if (Nstate == 1) then
+
+    do ii=1,idx(0)
+      i_in_key = idx(ii)
+      i_in_coef = idx_key(idx(ii))
+      !DIR$ FORCEINLINE
+      call i_H_j(keys(1,1,i_in_key),key,Nint,hij)
+      i_H_psi_array(1) = i_H_psi_array(1) + coef(i_in_coef,1)*hij
+      call get_delta_e_dyall(keys(1,1,i_in_key),key,delta_e_final)
+
+      coef_pert +=  coef(i_in_coef,1)*hij / delta_e_final
+!     print*, 'delta_e_final = ',delta_e_final
+
+!     call i_H_j(key,key,Nint,hjj)
+!     coef_pert +=  coef(i_in_coef,1)*hij / (CI_electronic_energy(1) - hjj)
+    enddo
+    if     (coef_pert * i_H_psi_array(1) > 0.d0)then
+      print*, coef_pert * i_H_psi_array(1)
+    endif
+
+  else
+
+    do ii=1,idx(0)
+      i_in_key = idx(ii)
+      i_in_coef = idx_key(idx(ii))
+      !DIR$ FORCEINLINE
+      call i_H_j(keys(1,1,i_in_key),key,Nint,hij)
+      i_H_psi_array(1) = i_H_psi_array(1) + coef(i_in_coef,1)*hij
+      do j = 1, Nstate
+        i_H_psi_array(j) = i_H_psi_array(j) + coef(i_in_coef,j)*hij
+      enddo
+    enddo
+
+  endif
+
+end
+