diff --git a/CI/CI.ml b/CI/CI.ml
index 976d085..dff16fe 100644
--- a/CI/CI.ml
+++ b/CI/CI.ml
@@ -86,14 +86,7 @@ let create_matrix_spin f det_space =
     in
     let n_alfa = Array.length a in
     let n_beta = Array.length b in
-    let result = Array.init ndet (fun _ -> []) in
 
-    (** Update function when ki and kj are connected *)
-    let update i j ki kj =
-      let x = f ki kj in
-      if abs_float x > Constants.epsilon then
-        result.(i) <- (j, x) :: result.(i) ;
-    in
 
     (** Array of (list of singles, list of doubles) in the beta spin *)
     let degree_bb = 
@@ -123,9 +116,14 @@ let create_matrix_spin f det_space =
     let a = Array.to_list a
     and b = Array.to_list b
     in
-    let i = ref 0 in
-    List.iteri (fun ia i_alfa ->
-        Printf.eprintf "%8d / %8d\r%!" ia n_alfa;
+    let task i_alfa = 
+        let result = Array.init n_beta (fun _ -> []) in
+        (** Update function when ki and kj are connected *)
+        let update i j ki kj =
+          let x = f ki kj in
+          if abs_float x > Constants.epsilon then
+            result.(i) <- (j, x) :: result.(i) ;
+        in
         let j = ref 1 in
         let deg_a = Spindeterminant.degree i_alfa in
         List.iter (fun j_alfa ->
@@ -133,7 +131,7 @@ let create_matrix_spin f det_space =
             begin
               match degree_a with
               | 2 ->
-                let i' = ref !i in
+                let i' = ref 0 in
                 List.iteri (fun ib i_beta ->
                     let ki = Determinant.of_spindeterminants i_alfa i_beta in
                     let kj = Determinant.of_spindeterminants j_alfa i_beta in
@@ -141,7 +139,7 @@ let create_matrix_spin f det_space =
                     incr i';
                   ) b;
               | 1 -> 
-                let i' = ref !i in
+                let i' = ref 0 in
                 List.iteri (fun ib i_beta ->
                     let ki = Determinant.of_spindeterminants i_alfa i_beta in
                     let singles, _ = degree_bb.(ib) in
@@ -152,7 +150,7 @@ let create_matrix_spin f det_space =
                     incr i';
                   ) b;
               | 0 ->
-                let i' = ref !i in
+                let i' = ref 0 in
                 List.iteri (fun ib i_beta ->
                     let ki = Determinant.of_spindeterminants i_alfa i_beta in
                     let _singles, doubles = degree_bb.(ib) in
@@ -166,13 +164,22 @@ let create_matrix_spin f det_space =
             end;
             j := !j + n_beta
           ) a;
+          Array.map (fun l ->
+              List.rev l
+              |> Vector.sparse_of_assoc_list ndet
+          ) result 
+    in
+    let result =
+      Array.init ndet (fun _ -> Vector.sparse_of_assoc_list 0 [])
+    in
+    let i = ref 0 in
+    List.iteri (fun ia i_alfa ->
+        task i_alfa 
+        |> Array.iteri (fun j x -> result.(!i+j) <- x);
+        Printf.eprintf "%8d / %8d\r%!" (ia+1) n_alfa;
         i := !i + n_beta
       ) a;
-
-    Array.map (fun l ->
-        List.rev l
-        |> Vector.sparse_of_assoc_list ndet ) result
-    |> Matrix.sparse_of_vector_array
+    Matrix.sparse_of_vector_array result
   )