diff --git a/src/Bitmask/README.rst b/src/Bitmask/README.rst
index 4169d164..ada78e34 100644
--- a/src/Bitmask/README.rst
+++ b/src/Bitmask/README.rst
@@ -57,9 +57,15 @@ Documentation
 `full_ijkl_bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Bitmask/bitmasks.irp.f#L12>`_
   Bitmask to include all possible MOs
 
+`generators_bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Bitmask/bitmasks.irp.f#L91>`_
+  Bitmasks for generator determinants. (N_int, alpha/beta, hole/particle, generator)
+
 `hf_bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Bitmask/bitmasks.irp.f#L32>`_
   Hartree Fock bit mask
 
+`n_generators_bitmask <http://github.com/LCPQ/quantum_package/tree/master/src/Bitmask/bitmasks.irp.f#L58>`_
+  Number of bitmasks for generators
+
 `n_int <http://github.com/LCPQ/quantum_package/tree/master/src/Bitmask/bitmasks.irp.f#L3>`_
   Number of 64-bit integers needed to represent determinants as binary strings
 
diff --git a/src/Bitmask/bitmasks.ezfio_config b/src/Bitmask/bitmasks.ezfio_config
new file mode 100644
index 00000000..f402ef02
--- /dev/null
+++ b/src/Bitmask/bitmasks.ezfio_config
@@ -0,0 +1,8 @@
+bitmasks
+  N_int         integer
+  bit_kind      integer
+  N_mask_gen    integer
+  generators    integer (bitmasks_N_int*bitmasks_bit_kind/4,2,2,bitmasks_N_mask_gen)
+  N_mask_ref    integer
+  reference     integer (bitmasks_N_int*bitmasks_bit_kind/4,2,2,bitmasks_N_mask_ref)
+
diff --git a/src/Bitmask/bitmasks.irp.f b/src/Bitmask/bitmasks.irp.f
index ccdff541..3aa71421 100644
--- a/src/Bitmask/bitmasks.irp.f
+++ b/src/Bitmask/bitmasks.irp.f
@@ -55,4 +55,57 @@ BEGIN_PROVIDER [ integer(bit_kind), ref_bitmask, (N_int,2)]
  ref_bitmask = HF_bitmask
 END_PROVIDER
 
+BEGIN_PROVIDER [ integer, N_generators_bitmask ]
+ implicit none
+ BEGIN_DOC
+ ! Number of bitmasks for generators
+ END_DOC
+ logical                        :: exists
+ PROVIDE ezfio_filename
+ 
+ call ezfio_has_bitmasks_N_mask_gen(exists)
+ if (exists) then
+   call ezfio_get_bitmasks_N_mask_gen(N_generators_bitmask)
+   integer                        :: N_int_check
+   integer                        :: bit_kind_check
+   call ezfio_get_bitmasks_bit_kind(bit_kind_check)
+   if (bit_kind_check /= bit_kind) then
+     print *,  bit_kind_check, bit_kind
+     print *,  'Error: bit_kind is not correct in EZFIO file'
+   endif
+   call ezfio_get_bitmasks_N_int(N_int_check)
+   if (N_int_check /= N_int) then
+     print *,  N_int_check, N_int
+     print *,  'Error: N_int is not correct in EZFIO file'
+   endif
+ else
+   N_generators_bitmask = 1
+   call ezfio_set_bitmasks_N_int(N_int)
+   call ezfio_set_bitmasks_bit_kind(bit_kind)
+   call ezfio_set_bitmasks_N_mask_gen(N_generators_bitmask)
+ endif
+ ASSERT (N_generators_bitmask > 0)
+
+END_PROVIDER
+
+BEGIN_PROVIDER [ integer(bit_kind), generators_bitmask, (N_int,2,2,N_generators_bitmask) ]
+ implicit none
+ BEGIN_DOC
+ ! Bitmasks for generator determinants. (N_int, alpha/beta, hole/particle, generator)
+ END_DOC
+ logical                        :: exists
+ PROVIDE ezfio_filename
+
+ call ezfio_has_bitmasks_generators(exists)
+ if (exists) then
+   call ezfio_get_bitmasks_generators(generators_bitmask)
+ else
+   generators_bitmask(:,:,1,1) = HF_bitmask
+   generators_bitmask(:,1,2,1) = iand(not(HF_bitmask(:,1)),full_ijkl_bitmask(:,1))
+   generators_bitmask(:,2,2,1) = iand(not(HF_bitmask(:,2)),full_ijkl_bitmask(:,2))
+   call ezfio_set_bitmasks_generators(generators_bitmask)
+ endif
+ ASSERT (N_generators_bitmask > 0)
+
+END_PROVIDER
 
diff --git a/src/CISD/H_apply.irp.f b/src/CISD/H_apply.irp.f
index b589a38f..15582375 100644
--- a/src/CISD/H_apply.irp.f
+++ b/src/CISD/H_apply.irp.f
@@ -49,19 +49,16 @@ subroutine H_apply_cisd
   
   integer(bit_kind)              :: hole_mask(N_int,2)
   integer(bit_kind)              :: particle_mask(N_int,2)
-  hole_mask(:,1) = HF_bitmask(:,1)
-  hole_mask(:,2) = HF_bitmask(:,2)
-  particle_mask(:,1) = iand(not(HF_bitmask(:,1)),full_ijkl_bitmask(:,1))
-  particle_mask(:,2) = iand(not(HF_bitmask(:,2)),full_ijkl_bitmask(:,2))
-
-  PROVIDE N_det_generators
-
-  call H_apply_cisd_OpenMP_monoexc(HF_bitmask,                              &
-      hole_mask, particle_mask)
-  call H_apply_cisd_OpenMP_diexc(HF_bitmask,                                &
-      hole_mask, particle_mask,                                      &
-      hole_mask, particle_mask )
-
+  
+  ASSERT (N_det_generators == 1)
+  PROVIDE H_apply_buffer_allocated mo_bielec_integrals_in_map
+  
+  call H_apply_cisd_OpenMP_monoexc(HF_bitmask,                       &
+      generators_bitmask(:,:,1,1), generators_bitmask(:,:,2,1))
+  call H_apply_cisd_OpenMP_diexc(HF_bitmask,                         &
+      generators_bitmask(:,:,1,1), generators_bitmask(:,:,2,1),      &
+      generators_bitmask(:,:,1,1), generators_bitmask(:,:,2,1) )
+  
   call copy_h_apply_buffer_to_wf
 end
 
diff --git a/src/CISD/README.rst b/src/CISD/README.rst
index b50a6e18..a49b2be1 100644
--- a/src/CISD/README.rst
+++ b/src/CISD/README.rst
@@ -50,8 +50,5 @@ Documentation
 `repeat_excitation <http://github.com/LCPQ/quantum_package/tree/master/src/CISD/SC2.irp.f#L143>`_
   Undocumented
 
-`cisd <http://github.com/LCPQ/quantum_package/tree/master/src/CISD/cisd_sc2.irp.f#L1>`_
-  Undocumented
-