Preparation of Schwartz screening

Basis/Shell_pair.ml

@@ -39,12 +39,6 @@ let create_array ?cutoff p_a p_b =
 
       Array.init (Contracted_shell.size p_b) (fun j ->
           try
-            if Contracted_shell.center p_a = Contracted_shell.center p_b &&
-              ((Angular_momentum.to_int @@ Contracted_shell.totAngMom p_a) +
-               (Angular_momentum.to_int @@ Contracted_shell.totAngMom p_b)) land 1 = 1
-            then
-              raise Null_contribution;
-
             let f2 =
               Contracted_shell.norm_coef p_b j
             in

Basis/TwoElectronRR.ml

@@ -1,5 +1,8 @@
 open Util
 
+let cutoff2 = cutoff *. cutoff
+
+exception NullQuartet
 
 (** Horizontal and Vertical Recurrence Relations (HVRR) *)
 let hvrr_two_e m (angMom_a, angMom_b, angMom_c, angMom_d)
@@ -20,9 +23,6 @@ let hvrr_two_e m (angMom_a, angMom_b, angMom_c, angMom_d)
   (** Vertical recurrence relations *)
   let rec vrr m angMom_a angMom_c totAngMom_a totAngMom_c =
 
-    if    angMom_a.(0) < 0 || angMom_a.(1) < 0 || angMom_a.(2) < 0
-       || angMom_c.(0) < 0 || angMom_c.(1) < 0 || angMom_c.(2) < 0 then 0.
-    else
     match (totAngMom_a, totAngMom_c) with
     | (0,0) -> zero_m_array.(m)
     | (_,0) ->
@@ -44,14 +44,16 @@ let hvrr_two_e m (angMom_a, angMom_b, angMom_c, angMom_d)
                         in
                         am.(xyz)  <- am.(xyz) - 1;
                         amm.(xyz) <- amm.(xyz) - 2;
+                        if am.(xyz) < 0 then 0. else
                           chop (-. expo_b *. expo_inv_p *. (Coordinate.coord center_ab xyz))
                             (fun () -> vrr m am angMom_c (totAngMom_a-1) totAngMom_c )
                           +. chop (expo_inv_p *. (Coordinate.coord center_pq xyz)) 
                             (fun () ->  vrr (m+1) am angMom_c (totAngMom_a-1) totAngMom_c )
-                          +. chop ((float_of_int am.(xyz)) *. expo_inv_p *. 0.5)
+                          +. (if amm.(xyz) < 0 then 0. else
+                                chop ((float_of_int am.(xyz)) *. expo_inv_p *. 0.5)
                                   (fun () ->  vrr m amm angMom_c (totAngMom_a-2) totAngMom_c
                                               +. chop expo_inv_p (fun () ->
-                                            vrr (m+1) amm angMom_c (totAngMom_a-2) totAngMom_c) ) )
+                                                  vrr (m+1) amm angMom_c (totAngMom_a-2) totAngMom_c) ) ) )
       in
       if not found then
         Zmap.add map.(m) key result;
@@ -79,16 +81,19 @@ let hvrr_two_e m (angMom_a, angMom_b, angMom_c, angMom_d)
                         am.(xyz)  <- am.(xyz)  - 1;
                         cm.(xyz)  <- cm.(xyz)  - 1;
                         cmm.(xyz) <- cmm.(xyz) - 2;
+                        if cm.(xyz) < 0 then 0. else
                           chop (-. expo_d *. expo_inv_q *. (Coordinate.coord center_cd xyz) )
                             (fun () ->  vrr m angMom_a cm totAngMom_a (totAngMom_c-1) )
                           -. chop (expo_inv_q *. (Coordinate.coord center_pq xyz))
                             (fun () -> vrr (m+1) angMom_a cm totAngMom_a (totAngMom_c-1) )
-                          +. chop ((float_of_int cm.(xyz)) *. expo_inv_q *. 0.5 )
+                          +. (if cmm.(xyz) < 0 then 0. else
+                                chop ((float_of_int cm.(xyz)) *. expo_inv_q *. 0.5 )
                                   (fun () -> vrr m angMom_a cmm totAngMom_a (totAngMom_c-2)
                                              +. chop expo_inv_q
-                                         (fun () -> vrr (m+1) angMom_a cmm totAngMom_a (totAngMom_c-2) ) )
+                                               (fun () -> vrr (m+1) angMom_a cmm totAngMom_a (totAngMom_c-2) ) ) )
-                          -. chop ((float_of_int angMom_a.(xyz)) *. expo_inv_p *. expo_inv_q *. 0.5 )
+                          -. (if am.(xyz) lor cm.(xyz) < 0 then 0. else
-                            (fun () -> vrr (m+1) am cm (totAngMom_a-1) (totAngMom_c-1) ) )
+                                chop ((float_of_int angMom_a.(xyz)) *. expo_inv_p *. expo_inv_q *. 0.5 )
+                                  (fun () -> vrr (m+1) am cm (totAngMom_a-1) (totAngMom_c-1) ) ))
       in
       if not found then
         Zmap.add map.(m) key result;
@@ -101,9 +106,6 @@ let hvrr_two_e m (angMom_a, angMom_b, angMom_c, angMom_d)
   and hrr m angMom_a angMom_b angMom_c angMom_d
       totAngMom_a totAngMom_b totAngMom_c totAngMom_d =
 
-    if    angMom_b.(0) < 0 || angMom_b.(1) < 0 || angMom_b.(2) < 0
-       || angMom_d.(0) < 0 || angMom_d.(1) < 0 || angMom_d.(2) < 0 then 0.
-    else
     match (totAngMom_b, totAngMom_d) with
     | (0,0) -> vrr m angMom_a angMom_c totAngMom_a totAngMom_c
     | (_,_) ->
@@ -131,8 +133,9 @@ let hvrr_two_e m (angMom_a, angMom_b, angMom_c, angMom_d)
                             in
                             ap.(xyz) <- ap.(xyz) + 1;
                             bm.(xyz) <- bm.(xyz) - 1;
-                              hrr m ap bm angMom_c angMom_d (totAngMom_a+1) (totAngMom_b-1)
+                            if (bm.(xyz) < 0) then 0. else
-                                totAngMom_c totAngMom_d
+                              hrr m ap bm angMom_c angMom_d
+                                (totAngMom_a+1) (totAngMom_b-1) totAngMom_c totAngMom_d
                               +. chop (Coordinate.coord center_ab xyz) (fun () ->
                                   hrr m angMom_a bm angMom_c angMom_d totAngMom_a (totAngMom_b-1)
                                     totAngMom_c totAngMom_d )
@@ -185,6 +188,15 @@ let contracted_class ~zero_m shell_a shell_b shell_c shell_d : float Zmap.t =
                            totAngMom shell_c, totAngMom shell_d))
   in
 
+  (*
+  (* Precomputation of overlaps *)
+  let overlaps_p =
+    Overlap.contracted_class shell_a shell_b
+  and overlaps_q =
+    Overlap.contracted_class shell_c shell_d
+  in
+  *)
+
   let contracted_class = 
     Array.make (Array.length class_indices) 0.;
   in
@@ -197,12 +209,14 @@ let contracted_class ~zero_m shell_a shell_b shell_c shell_d : float Zmap.t =
 
     for cd=0 to (Array.length shell_q - 1)
     do
+      try
         let coef_prod =
           shell_p.(ab).Shell_pair.coef *. shell_q.(cd).Shell_pair.coef
         in
-      (** Screening on thr product of coefficients *)
+        (** Screening on the product of coefficients *)
-      if (abs_float coef_prod) > 1.e-4*.cutoff then
+        if (abs_float coef_prod) < 1.e-4*.cutoff then
-        begin
+          raise NullQuartet;
+
 
         let expo_pq_inv =
           shell_p.(ab).Shell_pair.expo_inv +. shell_q.(cd).Shell_pair.expo_inv
@@ -241,6 +255,25 @@ let contracted_class ~zero_m shell_a shell_b shell_c shell_d : float Zmap.t =
                   [| a.(6) ;  a.(7) ;  a.(8) |], 
                   [| a.(9) ; a.(10) ; a.(11) |] )
               in
+              try
+              (*
+                (* Schwartz screening *)
+                let schwartz_p =
+                  Zmap.find overlaps_p @@ Zkey.of_int_array ~kind:Zkey.Kind_6
+                    [| angMomA.(0) ; angMomA.(1) ; angMomA.(2) ; 
+                       angMomB.(0) ; angMomB.(1) ; angMomB.(2) |]
+                  |> abs_float
+                in
+                let schwartz_q =
+                  Zmap.find overlaps_q @@ Zkey.of_int_array ~kind:Zkey.Kind_6
+                    [| angMomC.(0) ; angMomC.(1) ; angMomC.(2) ; 
+                       angMomD.(0) ; angMomD.(1) ; angMomD.(2) |]
+                  |> abs_float
+                in
+                if schwartz_p*.schwartz_q = 0. then
+                  () ; (*raise NullQuartet; *)
+                  *)
+                
                 let norm = 
                   shell_p.(ab).Shell_pair.norm_fun angMomA angMomB *. shell_q.(cd).Shell_pair.norm_fun angMomC angMomD 
                 in
@@ -255,8 +288,12 @@ let contracted_class ~zero_m shell_a shell_b shell_c shell_d : float Zmap.t =
                       map )
                 in
                 contracted_class.(i) <- contracted_class.(i) +. coef_prod *. integral
+                (*
+;if (schwartz_p*.schwartz_q < cutoff2) then Printf.printf "%e %e\n" (schwartz_p*.schwartz_q) integral;
+              *)
+              with NullQuartet -> ()
             ) class_indices
-        end
+      with NullQuartet -> ()
     done
   done;
   let result =