From a8ce1445859c8be4ff794648693b3f966e7848fd Mon Sep 17 00:00:00 2001
From: Patrick Shriwise <pshriwise@gmail.com>
Date: Wed, 31 Mar 2021 23:38:25 -0500
Subject: [PATCH] Resetting coordinates at lower levels in
 neighbor_list_find_cell.

---
 src/geometry.cpp | 10 +++++++++-
 src/particle.cpp |  4 ----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/geometry.cpp b/src/geometry.cpp
index 9d612412b..06d35cace 100644
--- a/src/geometry.cpp
+++ b/src/geometry.cpp
@@ -188,7 +188,9 @@ find_cell_inner(Particle& p, const NeighborList* neighbor_list)
       coord.r -= c.translation_;
 
       // Apply rotation.
-      coord.rotate(c.rotation_);
+      if (!c.rotation_.empty()) {
+        coord.rotate(c.rotation_);
+      }
 
     } else if (c.type_ == Fill::LATTICE) {
       //========================================================================
@@ -245,6 +247,12 @@ find_cell_inner(Particle& p, const NeighborList* neighbor_list)
 
 bool neighbor_list_find_cell(Particle& p)
 {
+
+  // Reset all the deeper coordinate levels.
+  for (int i = p.n_coord_; i < p.coord_.size(); i++) {
+    p.coord_[i].reset();
+  }
+
   // Get the cell this particle was in previously.
   auto coord_lvl = p.n_coord_ - 1;
   auto i_cell = p.coord_[coord_lvl].cell;
diff --git a/src/particle.cpp b/src/particle.cpp
index d05b81d84..2e2413174 100644
--- a/src/particle.cpp
+++ b/src/particle.cpp
@@ -38,10 +38,6 @@ namespace openmc {
 void
 LocalCoord::rotate(const std::vector<double>& rotation)
 {
-  if (rotation.empty()) {
-    this->rotated = false;
-    return;
-  }
   this->r = this->r.rotate(rotation);
   this->u = this->u.rotate(rotation);
   this->rotated = true;