Improved EN

CI/CI.ml

@@ -973,7 +973,35 @@ let is_internal det_space =
         Bitstring.logand neg_active_mask beta = occ_mask
 
 
-let _pt2_en ci =
+let is_external det_space =
+    let mo_class      = DeterminantSpace.mo_class det_space in
+    let numbits = Array.length @@ MOClass.mo_class_array mo_class in
+    let m l =
+      List.fold_left (fun accu i ->
+          let j = i-1 in
+          Bitstring.logor accu (Bitstring.shift_left_one numbits j)
+        ) (Bitstring.zero numbits) l
+    in
+    let inactive_mask = m (MOClass.inactive_mos mo_class) in
+    fun a ->
+      let alfa =
+        Determinant.alfa a
+        |> Spindeterminant.bitstring
+      in
+      let n_a = 
+	Bitstring.(popcount @@ logand inactive_mask alfa) 
+      in
+      match n_a with
+      | 0 | 1 | 2 -> 
+	let beta =
+	  Determinant.beta a
+	  |> Spindeterminant.bitstring
+	in
+	n_a + Bitstring.(popcount @@ logand inactive_mask beta) < 3 
+      | _ ->   false
+
+
+let pt2_en ci =
 
   let mo_basis  = Ds.mo_basis ci.det_space in
   let psi0, e0 = Parallel.broadcast ci.eigensystem in
@@ -1038,7 +1066,7 @@ let _pt2_en ci =
   |> List.fold_left (+.) 0.
 
 
-let pt2_en ci =
+let _pt2_en ci =
 
   let mo_basis  = Ds.mo_basis ci.det_space in
   let psi0, e0 = Parallel.broadcast ci.eigensystem in
@@ -1117,11 +1145,37 @@ let pt2_en_reference ci =
   let ds =
     DeterminantSpace.fci_of_mo_basis ~frozen_core:false aux_basis
   in
+
+  let det_stream =
+    let e =
+      let f = is_external ci.det_space  in
+      function
+      | None -> false
+      | Some d -> f d
+    in
+    let stream =
+      DeterminantSpace.determinant_stream ds
+    in
+    let rec next i =
+      let det =
+        try
+          Some (Stream.next stream)
+        with Stream.Failure -> None
+      in
+      if det = None then
+        None
+      else
+        if e det then
+          det
+        else
+          (next [@tailcall]) i
+    in
+    Stream.from next
+  in
+
   let out_dets =
-    ds
-    |> DeterminantSpace.determinants_array                                                    
-    |> Array.to_list
-    |> List.filter (fun i -> not (is_internal ci.det_space i))
+    det_stream
+    |> stream_to_list
     |> Array.of_list
   in
 

run_cas.ml

@@ -95,10 +95,8 @@ let () =
   if Parallel.master then
     Format.fprintf ppf "CAS-CI energy : %20.16f@." ((CI.eigenvalues ci).{1} +. Simulation.nuclear_repulsion s);
 
-(*
   let pt2 = CI.pt2_mp ci in
   Format.fprintf ppf "CAS-MP2 energy : %20.16f@." ((CI.eigenvalues ci).{1} +. Simulation.nuclear_repulsion s +. pt2);
-*)
 
 
   let pt2 = CI.pt2_en ci in