Store ERI in a genarray

Basis/ERI.ml

@@ -2,6 +2,7 @@
 
 open Util
 open Constants
+open Bigarray
 
 (** (00|00)^m : Fundamental electron repulsion integral
     $ \int \int \phi_p(r1) 1/r_{12} \phi_q(r2) dr_1 dr_2 $
@@ -44,6 +45,19 @@ type n_cls = { n : int ; cls : Z.t array }
 *)
 exception NullIntegral
 
+(*
+(** Unique index for integral <ij|kl> *)
+let index i j k l =
+  let f i k = 
+    let (p,r) = 
+      if i <= k then (i,k) else (k,i)
+    in p+ (r*r-r)/2
+  in
+  let p = f i k and q = f j l in
+  f p q
+*)
+
+
 (** Write all integrals to a file with the <ij|kl> convention *)
 let to_file ~filename basis =
   let to_int_tuple x = 
@@ -63,6 +77,8 @@ let to_file ~filename basis =
   Printf.printf "%d shells\n" (Array.length basis);
 
   (* Pre-compute diagonal integrals for Schwartz *)
+  let t0 = Unix.gettimeofday () in
+
   let schwartz = 
     Array.map (fun pair_array -> Array.map (fun pair ->
         let cls = 
@@ -81,7 +97,21 @@ let to_file ~filename basis =
           icount := !icount + 1;
     done;
   done;
-  Printf.printf "%d shell pairs\n" !icount;
+  Printf.printf "%d shell pairs computed in %f seconds\n" !icount (Unix.gettimeofday () -. t0);
+
+  let eri_array = 
+
+    let n = ref 0 in
+    for i=0 to (Array.length basis) - 1 do
+      n := !n + (Array.length (basis.(i).Contracted_shell.powers))
+    done;
+    let n = !n in
+    Genarray.create Float64 c_layout [| n ; n ; n ; n|]
+  in
+  Genarray.fill eri_array 0.;
+
+  (* Compute ERIs *)
+  let t0 = Unix.gettimeofday () in
 
   let inn = ref 0 and out = ref 0 in
 
@@ -147,12 +177,8 @@ let to_file ~filename basis =
                             in
                             if (abs_float value > cutoff) then
                               (inn := !inn + 1;
-                              (*
-                              assert ((i_c, k_c, j_c, l_c) <> (-1,0,0,0));
-                                *)
-                              Printf.fprintf oc "%4d %4d %4d %4d %20.12e\n"
-                                i_c k_c j_c l_c value
-                                )
+                              eri_array.{(i_c-1),(k_c-1),(j_c-1),(l_c-1)} <- value;
+                              )
                             else
                               out := !out + 1;
                           ) basis.(l).Contracted_shell.powers 
@@ -165,6 +191,36 @@ let to_file ~filename basis =
       with NullIntegral -> ()
     done;
   done;
+
+  Printf.printf "Computed %d non-zero ERIs in %f seconds\n" !inn (Unix.gettimeofday () -. t0);
+
+  (* Print ERIs *)
+  for i=0 to (Array.length basis) - 1 do
+    print_int basis.(i).Contracted_shell.indice ; print_newline ();
+    for j=0 to i do
+        for k=0 to i do
+          for l=0 to k do
+            (* Write the data in the output file *)
+            Array.iteri (fun i_c _ ->
+                let i_c = basis.(i).Contracted_shell.indice + i_c + 1 in
+                Array.iteri (fun j_c _ ->
+                    let j_c = basis.(j).Contracted_shell.indice + j_c + 1 in
+                    Array.iteri (fun k_c _ ->
+                        let k_c = basis.(k).Contracted_shell.indice + k_c + 1 in 
+                        Array.iteri (fun l_c _ ->
+                            let l_c = basis.(l).Contracted_shell.indice + l_c + 1 in
+                            let value = eri_array.{(i_c-1),(k_c-1),(j_c-1),(l_c-1)} in
+                            if (value <> 0.) then
+                              Printf.fprintf oc "%4d %4d %4d %4d %20.12e\n"
+                                i_c k_c j_c l_c value;
+                          ) basis.(l).Contracted_shell.powers 
+                      ) basis.(k).Contracted_shell.powers
+                  ) basis.(j).Contracted_shell.powers
+              ) basis.(i).Contracted_shell.powers;
+          done;
+        done;
+    done;
+  done;
   Printf.printf "In: %d  Out:%d\n" !inn !out ;
   close_out oc
 

_tags

@@ -1,3 +1,3 @@
-true: package(str,zarith)
+true: package(str,unix,bigarray,zarith)
 <*.byte>  : linkdep(Utils/math_functions.o), custom
 <*.native>: linkdep(Utils/math_functions.o)