From ec874e261521155241698fd1f8776040b1670e02 Mon Sep 17 00:00:00 2001
From: Anthony Scemama <scemama@irsamc.ups-tlse.fr>
Date: Thu, 10 Dec 2020 10:43:13 +0100
Subject: [PATCH] Added seniority keyword in cipsi

---
 src/cipsi/selection.irp.f | 14 ++++++++++++++
 src/fci/EZFIO.cfg         |  6 +++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/cipsi/selection.irp.f b/src/cipsi/selection.irp.f
index fd434c1e..2c35a98f 100644
--- a/src/cipsi/selection.irp.f
+++ b/src/cipsi/selection.irp.f
@@ -821,6 +821,19 @@ subroutine fill_buffer_double(i_generator, sp, h1, h2, bannedOrb, banned, fock_d
         enddo
       endif
 
+      if (seniority >= 0) then
+        !TODO : Check if 1st determinant should be used for all states
+        integer :: s
+        s = 0
+        do k=1,N_int
+          s = s + popcnt(ieor(det(k,1),det(k,2)))
+        enddo
+
+        if (s > seniority) then
+          e_pert(:) = 0.d0
+        endif
+      endif
+
 
 !      ! Gram-Schmidt using input overlap matrix
 !      do istate=1,N_states
@@ -900,6 +913,7 @@ subroutine fill_buffer_double(i_generator, sp, h1, h2, bannedOrb, banned, fock_d
 
 !      w = dble(n) * w
 
+
       if(w <= buf%mini) then
         call add_to_selection_buffer(buf, det, w)
       end if
diff --git a/src/fci/EZFIO.cfg b/src/fci/EZFIO.cfg
index d5526673..69b6c502 100644
--- a/src/fci/EZFIO.cfg
+++ b/src/fci/EZFIO.cfg
@@ -10,4 +10,8 @@ doc: Calculated |FCI| energy + |PT2|
 interface: ezfio
 size: (determinants.n_states)
 
-
+[seniority]
+type: integer
+doc: Using -1 selects all determinants
+interface: ezfio,ocaml,provider
+default: -1