diff --git a/ocaml/.merlin b/ocaml/.merlin
new file mode 100644
index 0000000..ddf2226
--- /dev/null
+++ b/ocaml/.merlin
@@ -0,0 +1,3 @@
+PKG core cryptokit str ZMQ
+S .
+
diff --git a/ocaml/QmcMd5.ml b/ocaml/QmcMd5.ml
new file mode 100644
index 0000000..fa177f1
--- /dev/null
+++ b/ocaml/QmcMd5.ml
@@ -0,0 +1,149 @@
+open Core
+
+(** Directory containing the list of input files. The directory is created is inexistant. *)
+let input_directory = lazy (
+
+  let ezfio_filename =
+    Lazy.force Qputils.ezfio_filename
+  in
+
+  let dirname = 
+    Filename.concat ezfio_filename "input"
+  in
+
+  begin
+    match ( Sys.is_directory dirname ) with
+    | `No  -> Unix.mkdir  dirname
+    | _    -> ()
+  end ;
+
+  dirname
+)
+
+
+(** List of files responsible for the MD5 key of the input *)
+let files_to_track = [
+  "ao_basis/ao_coef.gz" ;
+  "ao_basis/ao_expo.gz" ;
+  "ao_basis/ao_nucl.gz" ;
+  "ao_basis/ao_num" ; 
+  "ao_basis/ao_power.gz" ;
+  "ao_basis/ao_prim_num.gz" ; 
+  "electrons/elec_alpha_num" ;
+  "electrons/elec_beta_num" ;
+  "electrons/elec_walk_num" ;
+  "jastrow/jast_type" ;
+  "mo_basis/mo_coef.gz" ;
+  "mo_basis/mo_tot_num" ;
+  "nuclei/nucl_charge.gz" ;
+  "nuclei/nucl_coord.gz" ;
+  "nuclei/nucl_num" ;
+  "simulation/ci_threshold" ;
+  "simulation/nucl_fitcusp_factor" ;
+  "simulation/jast_a_up_dn" ;
+  "simulation/jast_a_up_up" ;
+  "simulation/jast_b_up_dn" ;
+  "simulation/jast_b_up_up" ;
+  "simulation/jast_core_a1" ;
+  "simulation/jast_core_a2" ;
+  "simulation/jast_core_b1" ;
+  "simulation/jast_core_b2" ;
+  "simulation/jast_een_e_a.gz" ;
+  "simulation/jast_een_e_b.gz" ;
+  "simulation/jast_een_n.gz" ;
+  "simulation/jast_pen.gz" ;
+  "simulation/method" ;
+  "simulation/time_step" ;
+  "simulation/dmc_projection_time" ;
+  "spindeterminants/bit_kind" ;
+  "spindeterminants/n_det" ;
+  "spindeterminants/n_det_alpha" ;
+  "spindeterminants/n_det_beta" ;
+  "spindeterminants/n_int" ;
+  "spindeterminants/n_states" ;
+  "spindeterminants/psi_coef_matrix_columns.gz" ;
+  "spindeterminants/psi_coef_matrix_rows.gz" ;
+  "spindeterminants/psi_coef_matrix_values.gz" ;
+  "spindeterminants/psi_det_alpha.gz" ;
+  "spindeterminants/psi_det_beta.gz" ;
+  "/pseudo/do_pseudo" ;
+  "/pseudo/mo_pseudo_grid.gz" ;
+  "/pseudo/pseudo_dz_kl.gz";
+  "/pseudo/pseudo_klocmax" ;
+  "/pseudo/pseudo_n_k.gz" ;
+  "/pseudo/pseudo_v_kl.gz" ;
+  "/pseudo/pseudo_grid_rmax" ;
+  "/pseudo/pseudo_kmax" ;
+  "/pseudo/pseudo_n_kl.gz" ;
+  "/pseudo/pseudo_dz_k.gz" ;
+  "/pseudo/pseudo_grid_size" ;
+  "/pseudo/pseudo_v_k.gz" ;
+  ]
+
+
+(** Get an MD5 ke from the content of a file. *)
+let hash_file filename =
+  match Sys.is_file filename with
+  | `Yes -> 
+    begin
+      In_channel.with_file filename ~f:(fun ic ->
+        Cryptokit.hash_channel (Cryptokit.Hash.md5 ()) ic
+        |> Cryptokit.transform_string (Cryptokit.Hexa.encode ()) )
+    end
+  | _ -> ""
+  
+
+(** Cache containing the current value of the MD5 hash. *)
+let _hash = 
+  ref None
+
+(** Get the hash correcponding to the EZFIO file. *)
+let hash () = 
+  let compute_hash () =
+    let ezfio_filename =
+      Lazy.force Qputils.ezfio_filename
+    in
+    let old_md5 =
+      if Ezfio.has_simulation_md5_key () then
+         Ezfio.get_simulation_md5_key ()
+      else
+         ""
+    in
+    let md5_string = 
+      files_to_track
+      |> List.map ~f:(fun x -> Printf.sprintf "%s/%s" ezfio_filename x)
+      |> List.map ~f:hash_file
+      |> String.concat
+    in
+
+    let new_md5 = 
+      md5_string
+      |> Cryptokit.hash_string (Cryptokit.Hash.md5 ()) 
+      |> Cryptokit.transform_string (Cryptokit.Hexa.encode ()) 
+    in
+    if (new_md5 <> old_md5) then
+      begin
+        Printf.eprintf "Info : MD5 key changed\n   %s\n-> %s\n%!" old_md5 new_md5 ;
+        Ezfio.set_simulation_md5_key new_md5
+      end
+    ;
+    new_md5
+  in
+  match (!_hash) with
+  | Some key -> key
+  | None -> 
+      begin
+        let key =
+          compute_hash ()
+        in
+        _hash := Some key ;
+        key
+      end
+
+(** Reset the cache of the MD5 hash. *)
+let reset_hash () =
+  _hash := None;
+  ignore (hash ())
+
+
+