core: Fixed find_current_cell

src/core/cells.cpp

@@ -401,13 +401,11 @@ void cells_update_ghosts() {
 }
 
 Cell *find_current_cell(const Particle &p) {
-  auto c = cell_structure.position_to_cell(p.r.p.data());
-  if (c) {
-    return c;
-  } else if (!p.l.ghost) {
-    // Old pos must lie within the cell system
-    return cell_structure.position_to_cell(p.l.p_old.data());
-  } else {
+  assert(not resort_particles);
+
+  if (p.l.ghost) {
     return nullptr;
   }
+
+  return cell_structure.position_to_cell(p.l.p_old);
 }

src/core/cells.hpp

@@ -312,12 +312,11 @@ void local_sort_particles();
 
 /*@}*/
 
-/* @brief Finds the cell in which a particle is stored
-
-   Uses position_to_cell on p.r.p. If this is not on the node's domain,
-   uses position at last Verlet list rebuild (p.l.p_old).
-
-   @return pointer to the cell or nullptr if the particle is not on the node
+/**
+ * @brief Finds the cell in which a particle is stored
+ *
+ *
+ * @return pointer to the cell or nullptr if the particle is not on the node
 */
 Cell *find_current_cell(const Particle &p);