From 92a1952b0674e33cde1379690cb5a96412fd8f64 Mon Sep 17 00:00:00 2001
From: Miles Stoudenmire <miles.stoudenmire@gmail.com>
Date: Tue, 28 Apr 2020 22:48:56 -0400
Subject: [PATCH] Fix totalQN function to always succeed if lims set

---
 itensor/mps/mpsalgs.cc | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/itensor/mps/mpsalgs.cc b/itensor/mps/mpsalgs.cc
index cf98ff9bd..9648ecb0b 100644
--- a/itensor/mps/mpsalgs.cc
+++ b/itensor/mps/mpsalgs.cc
@@ -241,10 +241,14 @@ checkQNs(MPS const& psi)
 QN
 totalQN(MPS const& psi)
     {
-    const int center = findCenter(psi);
-    if(center == -1)
-        Error("Could not find ortho. center");
-    return div(psi(center));
+    auto tq = QN();
+    auto sj = psi.leftLim()+1;
+    auto ej = psi.rightLim()-1;
+    for(int j = sj; j <= ej; ++j)
+        {
+        tq += flux(psi(j));
+        }
+    return tq;
     }
 
 } //namespace itensor