diff --git a/ocaml/Input.ml b/ocaml/Input.ml
index 3d89aa78..a8980459 100644
--- a/ocaml/Input.ml
+++ b/ocaml/Input.ml
@@ -9,5 +9,6 @@ include Input_bitmasks;;
 include Input_cis;;
 include Input_cisd_sc2;;
 include Input_determinants;;
+include Input_electrons;;
 
 
diff --git a/ocaml/Input_electrons.ml b/ocaml/Input_electrons.ml
new file mode 100644
index 00000000..af016d08
--- /dev/null
+++ b/ocaml/Input_electrons.ml
@@ -0,0 +1,60 @@
+open Qptypes;;
+open Qputils;;
+open Core.Std;;
+
+module Electrons : sig
+  type t = 
+    { elec_alpha_num     : Strictly_positive_int.t;
+      elec_beta_num      : Positive_int.t;
+      elec_num           : Strictly_positive_int.t;
+    }
+  ;;
+  val read : unit -> t
+  val to_string : t -> string
+end = struct
+  type t = 
+    { elec_alpha_num     : Strictly_positive_int.t;
+      elec_beta_num      : Positive_int.t;
+      elec_num           : Strictly_positive_int.t;
+    }
+  ;;
+
+  let get_default = Qpackage.get_ezfio_default "electrons";;
+
+  let read_elec_alpha_num() = 
+    Ezfio.get_electrons_elec_alpha_num ()
+    |> Strictly_positive_int.of_int
+  ;;
+
+  let read_elec_beta_num() = 
+    Ezfio.get_electrons_elec_beta_num ()
+    |> Positive_int.of_int
+  ;;
+
+  let read_elec_num () = 
+    let na = Ezfio.get_electrons_elec_alpha_num ()
+    and nb = Ezfio.get_electrons_elec_beta_num  ()
+    in assert (na >= nb);
+    Strictly_positive_int.of_int (na + nb)
+  ;;
+
+
+  let read () = 
+    { elec_alpha_num      = read_elec_alpha_num ();
+      elec_beta_num       = read_elec_beta_num ();
+      elec_num            = read_elec_num ();
+    }
+  ;;
+
+  let to_string b =
+    Printf.sprintf "
+elec_alpha_num     = %s
+elec_beta_num      = %s
+elec_num           = %s
+"
+        (Strictly_positive_int.to_string b.elec_alpha_num)
+        (Positive_int.to_string b.elec_beta_num)
+        (Strictly_positive_int.to_string b.elec_num)
+end
+
+
diff --git a/ocaml/Molecule.ml b/ocaml/Molecule.ml
index 83691cdc..7e467ffb 100644
--- a/ocaml/Molecule.ml
+++ b/ocaml/Molecule.ml
@@ -19,7 +19,10 @@ let get_charge { nuclei  ; elec_alpha ; elec_beta } =
 ;;
 
 let get_multiplicity m = 
-  Multiplicity.of_alpha_beta m.elec_alpha m.elec_beta
+  let elec_alpha = m.elec_alpha
+  |> Positive_int.to_int
+  |> Strictly_positive_int.of_int in
+  Multiplicity.of_alpha_beta elec_alpha m.elec_beta
 ;;
 
 let get_nucl_num m =
diff --git a/ocaml/Multiplicity.ml b/ocaml/Multiplicity.ml
index 89246dec..a50d38ef 100644
--- a/ocaml/Multiplicity.ml
+++ b/ocaml/Multiplicity.ml
@@ -19,7 +19,7 @@ let to_string m =
 ;;
    
 let of_alpha_beta a b =
-  let a = Positive_int.to_int a 
+  let a = Strictly_positive_int.to_int a 
   and b = Positive_int.to_int b
   in
   assert (a >= b);
diff --git a/ocaml/qp_print.ml b/ocaml/qp_print.ml
index 5f11d394..0053b441 100644
--- a/ocaml/qp_print.ml
+++ b/ocaml/qp_print.ml
@@ -51,16 +51,20 @@ let run_i ~action ezfio_filename =
 
 
   let compute_charge () =
+    let input = Input.Electrons.read () in
     let nucl_charge = Ezfio.((get_nuclei_nucl_charge ()).data)
       |> Ezfio.flattened_ezfio_data |> Array.map ~f:(Float.to_int) 
-    and n_alpha = Ezfio.get_electrons_elec_alpha_num ()
-    and n_beta  = Ezfio.get_electrons_elec_beta_num ()
+    and n_alpha = input.Input.Electrons.elec_alpha_num
+      |> Strictly_positive_int.to_int
+    and n_beta  = input.Input.Electrons.elec_beta_num 
+      |> Positive_int.to_int
     in Array.fold ~init:(-n_alpha-n_beta) ~f:(fun x y -> x+y) nucl_charge
   in
 
   let compute_multiplicity () =
-    let n_alpha = Positive_int.of_int (Ezfio.get_electrons_elec_alpha_num ())
-    and n_beta  = Positive_int.of_int (Ezfio.get_electrons_elec_beta_num ())
+    let input = Input.Electrons.read () in
+    let n_alpha = input.Input.Electrons.elec_alpha_num
+    and n_beta  = input.Input.Electrons.elec_beta_num 
     in Multiplicity.of_alpha_beta n_alpha n_beta
   in
 
@@ -139,10 +143,10 @@ Prints data contained into the EZFIO file.
 Input data :
 
   * basis
-  * nuclei
+  * nucl
   * charge
-  * multiplicity
-  * electrons
+  * mult
+  * elec
 
 Output data :
 
@@ -150,6 +154,7 @@ Output data :
       ")
     spec
     (fun i o ezfio_file () ->
+  try 
       match (i,o) with
       | (Some i, None) -> run_i ~action:i ezfio_file
       | (None, Some o) -> run_o ~action:o ezfio_file
@@ -157,6 +162,9 @@ Output data :
           raise (Failure "Error : please specify -i or -o but not both.")
       | (None, None) -> 
           raise (Failure "Error : please specify -i or -o.")
+  with
+  | Failure msg -> print_string ("Error\n"^msg)
+  | _ -> ()
     )
 ;;
 
diff --git a/ocaml/qp_run.ml b/ocaml/qp_run.ml
index bbc9b625..5d860e03 100644
--- a/ocaml/qp_run.ml
+++ b/ocaml/qp_run.ml
@@ -77,7 +77,7 @@ let () =
   Command.basic
   ~summary: "Quantum Package command"
   ~readme:( fun () -> "
-Executes a Quantum Package binary file among these:\ni\n"
+Executes a Quantum Package binary file among these:\n\n"
 ^ (Lazy.force Qpackage.executables
     |> List.map ~f:(fun (x,_) -> Printf.sprintf " * %s" x )
     |> String.concat ~sep:"\n" 
diff --git a/ocaml/test_input.ml b/ocaml/test_input.ml
index 7135dcad..bd17a1b3 100644
--- a/ocaml/test_input.ml
+++ b/ocaml/test_input.ml
@@ -40,4 +40,11 @@ let test_cisd_sc2 () =
   print_endline (Input.Cisd_sc2.to_string b);
 ;;
 
-test_cisd_sc2();;
+let test_electrons () =
+  Ezfio.set_file "F2.ezfio" ;
+  let b = Input.Electrons.read ()
+  in
+  print_endline (Input.Electrons.to_string b);
+;;
+
+test_electrons();;