diff --git a/src/elements.f90 b/src/elements.f90
index 935b6f8..e9fc928 100644
--- a/src/elements.f90
+++ b/src/elements.f90
@@ -468,8 +468,8 @@ module elements
 
         do i = 1, atom_num
             do j = 1, 3
-                if (r_atom(j,i) > max_bd(j)) max_bd(j) = r_atom(j,i) + lim_zero
-                if (r_atom(j,i) < min_bd(j)) min_bd(j) = r_atom(j,i) - lim_zero
+                if (r_atom(j,i) > max_bd(j)) max_bd(j) = r_atom(j,i) + tol 
+                if (r_atom(j,i) < min_bd(j)) min_bd(j) = r_atom(j,i) - tol 
             end do 
         end do 
 
@@ -477,8 +477,8 @@ module elements
             do inod = 1, ng_node(lat_ele(i))
                 do ibasis = 1, basisnum(lat_ele(i))
                     do j = 1, 3
-                        if (r_node(j,ibasis,inod,i) > max_bd(j)) max_bd(j) = r_node(j,ibasis,inod,i) + lim_zero
-                        if (r_node(j,ibasis,inod,i) < min_bd(j)) min_bd(j) = r_node(j,ibasis,inod,i) -lim_zero
+                        if (r_node(j,ibasis,inod,i) > max_bd(j)) max_bd(j) = r_node(j,ibasis,inod,i) + tol
+                        if (r_node(j,ibasis,inod,i) < min_bd(j)) min_bd(j) = r_node(j,ibasis,inod,i) - tol
                     end do 
                 end do 
             end do 
diff --git a/src/parameters.f90 b/src/parameters.f90
index 2fa3e37..f261552 100644
--- a/src/parameters.f90
+++ b/src/parameters.f90
@@ -6,7 +6,8 @@ module parameters
     integer, parameter :: dp= selected_real_kind(15,307)
     !Parameters for floating point tolerance
     real(kind=dp), parameter :: lim_zero = epsilon(1.0_dp), &
-                                lim_large = huge(1.0_dp)
+                                lim_large = huge(1.0_dp), &
+                                tol = 10.0_dp**(-6.0_dp)
     logical, save :: lmpcac 
     
     !Numeric constants