diff --git a/src/DIELECTRIC/atom_vec_dielectric.h b/src/DIELECTRIC/atom_vec_dielectric.h
index b6b7ebd676..71aba900f8 100644
--- a/src/DIELECTRIC/atom_vec_dielectric.h
+++ b/src/DIELECTRIC/atom_vec_dielectric.h
@@ -35,9 +35,9 @@ class AtomVecDielectric : virtual public AtomVec {
   void grow_pointers() override;
   void create_atom_post(int) override;
   void data_atom_post(int) override;
-  void read_data_general_to_restricted(int, int);
-  void write_data_restricted_to_general();
-  void write_data_restore_restricted();
+  void read_data_general_to_restricted(int, int) override;
+  void write_data_restricted_to_general() override;
+  void write_data_restore_restricted() override;
 
   void unpack_restart_init(int) override;
   int property_atom(const std::string &) override;
diff --git a/src/DIPOLE/atom_vec_dipole.h b/src/DIPOLE/atom_vec_dipole.h
index 1f6d6fe2be..0b46195263 100644
--- a/src/DIPOLE/atom_vec_dipole.h
+++ b/src/DIPOLE/atom_vec_dipole.h
@@ -30,9 +30,9 @@ class AtomVecDipole : virtual public AtomVec {
 
   void grow_pointers() override;
   void data_atom_post(int) override;
-  void read_data_general_to_restricted(int, int);
-  void write_data_restricted_to_general();
-  void write_data_restore_restricted();
+  void read_data_general_to_restricted(int, int) override;
+  void write_data_restricted_to_general() override;
+  void write_data_restore_restricted() override;
 
  protected:
   double **mu;
diff --git a/src/MACHDYN/atom_vec_smd.h b/src/MACHDYN/atom_vec_smd.h
index 322136ebd3..47117c0b90 100644
--- a/src/MACHDYN/atom_vec_smd.h
+++ b/src/MACHDYN/atom_vec_smd.h
@@ -43,8 +43,8 @@ class AtomVecSMD : virtual public AtomVec {
   void force_clear(int, size_t) override;
   void create_atom_post(int) override;
   void data_atom_post(int) override;
-  void write_data_restricted_to_general();
-  void write_data_restore_restricted();
+  void write_data_restricted_to_general() override;
+  void write_data_restore_restricted() override;
 
  private:
   tagint *molecule;
diff --git a/src/SPIN/atom_vec_spin.h b/src/SPIN/atom_vec_spin.h
index 93bbc82ab8..7a2f890086 100644
--- a/src/SPIN/atom_vec_spin.h
+++ b/src/SPIN/atom_vec_spin.h
@@ -31,9 +31,9 @@ class AtomVecSpin : virtual public AtomVec {
   void grow_pointers() override;
   void force_clear(int, size_t) override;
   void data_atom_post(int) override;
-  void read_data_general_to_restricted(int, int);
-  void write_data_restricted_to_general();
-  void write_data_restore_restricted();
+  void read_data_general_to_restricted(int, int) override;
+  void write_data_restricted_to_general() override;
+  void write_data_restore_restricted() override;
 
  protected:
   double **sp, **fm, **fm_long;
diff --git a/src/atom.cpp b/src/atom.cpp
index d0614f923f..46b49fc6b6 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -50,6 +50,7 @@ using namespace MathConst;
 
 static constexpr int DELTA = 1;
 static constexpr double EPSILON = 1.0e-6;
+static constexpr double EPS_ZCOORD = 1.0e-12;
 
 /* ----------------------------------------------------------------------
    one instance per AtomVec style in style_atom.h
diff --git a/src/atom_vec_body.h b/src/atom_vec_body.h
index 0aa83e833f..5c7ed73d21 100644
--- a/src/atom_vec_body.h
+++ b/src/atom_vec_body.h
@@ -66,9 +66,9 @@ class AtomVecBody : public AtomVec {
   int pack_data_bonus(double *, int) override;
   void write_data_bonus(FILE *, int, double *, int) override;
 
-  void read_data_general_to_restricted(int, int);
-  void write_data_restricted_to_general();
-  void write_data_restore_restricted();
+  void read_data_general_to_restricted(int, int) override;
+  void write_data_restricted_to_general() override;
+  void write_data_restore_restricted() override;
 
   // methods used by other classes to query/set body info
 
diff --git a/src/atom_vec_ellipsoid.h b/src/atom_vec_ellipsoid.h
index 03850837d8..5b0d878c84 100644
--- a/src/atom_vec_ellipsoid.h
+++ b/src/atom_vec_ellipsoid.h
@@ -59,9 +59,9 @@ class AtomVecEllipsoid : public AtomVec {
   int pack_data_bonus(double *, int) override;
   void write_data_bonus(FILE *, int, double *, int) override;
 
-  void read_data_general_to_restricted(int, int);
-  void write_data_restricted_to_general();
-  void write_data_restore_restricted();
+  void read_data_general_to_restricted(int, int) override;
+  void write_data_restricted_to_general() override;
+  void write_data_restore_restricted() override;
 
   // unique to AtomVecEllipsoid