diff --git a/src/MC/fix_gcmc.cpp b/src/MC/fix_gcmc.cpp
index bc8e5b4316..c678bee4a7 100644
--- a/src/MC/fix_gcmc.cpp
+++ b/src/MC/fix_gcmc.cpp
@@ -1288,6 +1288,7 @@ void FixGCMC::attempt_atomic_deletion_full()
       atom->q[i] = 0.0;
     }
   }
+  if (force->kspace) force->kspace->qsum_qsq();
   double energy_after = energy_full();
 
   if (random_equal->uniform() < 
@@ -1305,6 +1306,7 @@ void FixGCMC::attempt_atomic_deletion_full()
       atom->mask[i] = tmpmask;
       if (atom->q_flag) atom->q[i] = q_tmp;
     }
+    if (force->kspace) force->kspace->qsum_qsq();
     energy_stored = energy_before;
   }
   update_gas_atoms_list();
@@ -1360,7 +1362,7 @@ void FixGCMC::attempt_atomic_insertion_full()
   }
   atom->nghost = 0;
   comm->borders();
-    
+  if (force->kspace) force->kspace->qsum_qsq();
   double energy_after = energy_full();
   
   if (random_equal->uniform() <
@@ -1371,6 +1373,7 @@ void FixGCMC::attempt_atomic_insertion_full()
   } else {
     atom->natoms--;
     if (proc_flag) atom->nlocal--;
+    if (force->kspace) force->kspace->qsum_qsq();
     energy_stored = energy_before;
   }
   update_gas_atoms_list();
@@ -1575,10 +1578,10 @@ void FixGCMC::attempt_molecule_deletion_full()
         m++;
         atom->q[i] = 0.0;
       }
-      
+      toggle_intramolecular(i);
     }
   }
-  
+  if (force->kspace) force->kspace->qsum_qsq();
   double energy_after = energy_full();  
 
   if (random_equal->uniform() < 
@@ -1600,12 +1603,14 @@ void FixGCMC::attempt_molecule_deletion_full()
     for (int i = 0; i < atom->nlocal; i++) {
       if (atom->molecule[i] == deletion_molecule) {
         atom->mask[i] = tmpmask[i];
+        toggle_intramolecular(i);
         if (atom->q_flag) {
           atom->q[i] = q_tmp[m];
           m++;
         }
       }    
     }
+    if (force->kspace) force->kspace->qsum_qsq();
   }
   update_gas_atoms_list();
 }
@@ -1720,6 +1725,7 @@ void FixGCMC::attempt_molecule_insertion_full()
   if (atom->map_style) atom->map_init();
   atom->nghost = 0;
   comm->borders();
+  if (force->kspace) force->kspace->qsum_qsq();
   double energy_after = energy_full();
 
   if (random_equal->uniform() < zz*volume*natoms_per_molecule*
@@ -1744,6 +1750,7 @@ void FixGCMC::attempt_molecule_insertion_full()
         atom->nlocal--;
       } else i++;
     }
+    if (force->kspace) force->kspace->qsum_qsq();
   }
   update_gas_atoms_list();
 }
@@ -1823,6 +1830,28 @@ tagint FixGCMC::pick_random_gas_molecule()
   return gas_molecule_id_all;
 }
 
+/* ----------------------------------------------------------------------
+------------------------------------------------------------------------- */
+
+void FixGCMC::toggle_intramolecular(int i)
+{
+  if (atom->avec->bonds_allow)
+    for (int m = 0; m < atom->num_bond[i]; m++) 
+      atom->bond_type[i][m] = -atom->bond_type[i][m];
+    
+  if (atom->avec->angles_allow)
+    for (int m = 0; m < atom->num_angle[i]; m++)
+      atom->angle_type[i][m] = -atom->angle_type[i][m];
+
+  if (atom->avec->dihedrals_allow)
+    for (int m = 0; m < atom->num_dihedral[i]; m++)
+      atom->dihedral_type[i][m] = -atom->dihedral_type[i][m];
+      
+  if (atom->avec->impropers_allow)
+    for (int m = 0; m < atom->num_improper[i]; m++)
+      atom->improper_type[i][m] = -atom->improper_type[i][m];
+}
+  
 /* ----------------------------------------------------------------------
    update the list of gas atoms
 ------------------------------------------------------------------------- */
diff --git a/src/MC/fix_gcmc.h b/src/MC/fix_gcmc.h
index 46db9ee41c..7e26d0709d 100644
--- a/src/MC/fix_gcmc.h
+++ b/src/MC/fix_gcmc.h
@@ -50,6 +50,7 @@ class FixGCMC : public Fix {
   double energy_full();
   int pick_random_gas_atom();
   tagint pick_random_gas_molecule();
+  void toggle_intramolecular(int);
   double molecule_energy(tagint);
   void update_gas_atoms_list();
   double compute_vector(int);
@@ -245,7 +246,7 @@ E: Illegal fix gcmc gas mass <= 0
 The computed mass of the designated gas molecule or atom type was less 
 than or equal to zero.
 
-E: Cannot do GCMC on atoms in atom_modify first group
+E: Cannot do gcmc on atoms in atom_modify first group
 
 This is a restriction due to the way atoms are organized in a list to
 enable the atom_modify first command.