diff --git a/Basis/Contracted_shell.ml b/Basis/Contracted_shell.ml
index bfa132f..091a2bb 100644
--- a/Basis/Contracted_shell.ml
+++ b/Basis/Contracted_shell.ml
@@ -63,7 +63,7 @@ let create ~indice ~expo ~coef ~center ~totAngMom =
   assert (Array.length expo > 0);
   let tmp =
     { indice ; expo ; coef ; center ; totAngMom ; size=Array.length expo ; norm_coef = [||];
-      powers = Angular_momentum.zkey_array (Angular_momentum.Kind_1 totAngMom) }
+      powers = Angular_momentum.zkey_array (Angular_momentum.Singlet totAngMom) }
   in
   { tmp with norm_coef = compute_norm_coef tmp }
 
diff --git a/Basis/TwoElectronRR.ml b/Basis/TwoElectronRR.ml
index 1d9289b..4861e15 100644
--- a/Basis/TwoElectronRR.ml
+++ b/Basis/TwoElectronRR.ml
@@ -185,7 +185,7 @@ let contracted_class ~zero_m shell_a shell_b shell_c shell_d : float Zmap.t =
   (* Pre-computation of integral class indices *)
   let class_indices = 
     Angular_momentum.zkey_array
-      (Angular_momentum.Kind_4 
+      (Angular_momentum.Quartet
         Contracted_shell.(totAngMom shell_a, totAngMom shell_b,
                           totAngMom shell_c, totAngMom shell_d))
   in
diff --git a/Utils/Angular_momentum.ml b/Utils/Angular_momentum.ml
index 7b443d6..f30b58a 100644
--- a/Utils/Angular_momentum.ml
+++ b/Utils/Angular_momentum.ml
@@ -53,9 +53,10 @@ let of_int = function
 
 
 type kind =
-| Kind_1 of  t
-| Kind_2 of (t*t)
-| Kind_4 of (t*t*t*t)
+| Singlet of  t
+| Doublet of (t*t)
+| Triplet of (t*t*t)
+| Quartet of (t*t*t*t)
 
 
 let n_functions a =
@@ -92,7 +93,7 @@ let zkey_array a =
 
   begin
     match a with
-    | Kind_1 l1 -> 
+    | Singlet l1 -> 
 
       let a = Array.init 3 (fun _ -> 0) in
       List.map (fun (cx,cy,cz) ->
@@ -100,7 +101,7 @@ let zkey_array a =
           Zkey.(of_int_array Kind_3 a)
         ) (keys_1d @@ to_int l1)
 
-    | Kind_2 (l1, l2) -> 
+    | Doublet (l1, l2) -> 
 
       let a = Array.init 6 (fun _ -> 0) in
       List.map (fun (cx,cy,cz) ->
@@ -110,9 +111,25 @@ let zkey_array a =
               Zkey.(of_int_array Kind_6 a)
             ) (keys_1d @@ to_int l1)
         ) (keys_1d @@ to_int l2)
-        |> List.concat
+      |> List.concat
 
-    | Kind_4 (l1, l2, l3, l4) ->
+    | Triplet (l1, l2, l3) ->
+
+      let a = Array.init 9 (fun _ -> 0) in
+      List.map (fun (ax,ay,az) ->
+          a.(0) <- ax ; a.(1) <- ay ; a.(2) <- az ;
+          List.map (fun (bx,by,bz) ->
+              a.(3) <- bx ; a.(4) <- by ; a.(5) <- bz ;
+              List.map (fun (cx,cy,cz) ->
+                  a.(6) <- cx ; a.(7) <- cy ; a.(8) <- cz ;
+                  Zkey.(of_int_array Kind_9 a)
+                ) (keys_1d @@ to_int l3)
+            ) (keys_1d @@ to_int l2)
+          |> List.concat
+        ) (keys_1d @@ to_int l1)
+      |> List.concat
+
+    | Quartet (l1, l2, l3, l4) ->
 
       let a = Array.init 12 (fun _ -> 0) in
       List.map (fun (ax,ay,az) ->
diff --git a/Utils/Angular_momentum.mli b/Utils/Angular_momentum.mli
index 73576a6..bc145d2 100644
--- a/Utils/Angular_momentum.mli
+++ b/Utils/Angular_momentum.mli
@@ -5,6 +5,11 @@ val to_string : t -> string
 val to_char : t -> char
 val to_int : t -> int
 val of_int : int -> t
-type kind = Kind_1 of t |  Kind_2 of (t * t) | Kind_4 of (t * t * t * t)
+type kind =
+| Singlet of  t
+| Doublet of (t*t)
+| Triplet of (t*t*t)
+| Quartet of (t*t*t*t)
+
 val n_functions : t -> int
 val zkey_array : kind -> Z.t array
diff --git a/Utils/Zkey.ml b/Utils/Zkey.ml
index 28e0d25..5c87239 100644
--- a/Utils/Zkey.ml
+++ b/Utils/Zkey.ml
@@ -6,6 +6,7 @@ type kind =
 | Kind_3
 | Kind_6
 | Kind_12
+| Kind_9
 | Kind_4
 | Kind_2
 | Kind_1
@@ -34,6 +35,14 @@ let of_int_array ~kind a =
       (Int64.of_int a.(6)) << a.(7) << a.(8) << a.(9) << a.(10) << a.(11)
       |> Z.of_int64 
      in a <| b
+  | Kind_9 ->
+    let a =
+      (Int64.of_int a.(0)) << a.(1) << a.(2) << a.(3) << a.(4) << a.(5)
+      |> Z.of_int64 
+     and b = 
+      (Int64.of_int a.(6)) << a.(7) << a.(8) 
+      |> Z.of_int64 
+     in a <| b
   | Kind_4 -> (Int64.of_int a.(0)) <+ a.(1) <+ a.(2) <+ a.(3) |> Z.of_int64
   | Kind_2 -> (Int64.of_int a.(0)) <+ a.(1) |> Z.of_int64
   | Kind_1 -> Z.of_int a.(0) 
@@ -63,6 +72,15 @@ let to_int_array ~kind a =
                   Z.to_int @@ Z.extract a  20 10 ;
                   Z.to_int @@ Z.extract a  10 10 ;
                   Z.to_int @@ Z.extract a   0 10 |]
+  | Kind_9 ->  [| Z.to_int @@ Z.extract a  84 10 ;
+                  Z.to_int @@ Z.extract a  74 10 ;
+                  Z.to_int @@ Z.extract a  64 10 ;
+                  Z.to_int @@ Z.extract a  50 10 ;
+                  Z.to_int @@ Z.extract a  40 10 ;
+                  Z.to_int @@ Z.extract a  30 10 ;
+                  Z.to_int @@ Z.extract a  20 10 ;
+                  Z.to_int @@ Z.extract a  10 10 ;
+                  Z.to_int @@ Z.extract a   0 10 |]
   | Kind_4  -> [| Z.to_int @@ Z.extract a  48 16 ;
                   Z.to_int @@ Z.extract a  32 16 ;
                   Z.to_int @@ Z.extract a  16 16 ;