diff --git a/src/Makefile b/src/Makefile
index feb933f..3b170e7 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2,7 +2,7 @@ FC=ifort
 FFLAGS=-mcmodel=large -g -O0 -stand f08 -fpe0 -traceback -check bounds,uninit -warn all -implicitnone -no-wrap-margin -heap-arrays
 #FFLAGS=-mcmodel=large -Ofast -no-wrap-margin -heap-arrays
 MODES=mode_create.o mode_merge.o mode_convert.o
-OPTIONS=opt_disl.o opt_group.o opt_orient.o opt_delete.o opt_deform.o opt_redef_box.o
+OPTIONS=opt_disl.o opt_group.o opt_orient.o opt_delete.o opt_deform.o opt_redef_box.o opt_slip_plane.o
 OBJECTS=main.o elements.o io.o subroutines.o functions.o atoms.o call_mode.o box.o  $(MODES) $(OPTIONS) call_option.o sorts.o
 
 .SUFFIXES:
diff --git a/src/call_option.f90 b/src/call_option.f90
index d55e1ee..af63333 100644
--- a/src/call_option.f90
+++ b/src/call_option.f90
@@ -6,6 +6,7 @@ subroutine call_option(option, arg_pos)
     use opt_deform
     use opt_delete
     use opt_redef_box
+    use opt_slip_plane
     use box
     implicit none
 
@@ -41,6 +42,8 @@ subroutine call_option(option, arg_pos)
         arg_pos=arg_pos +3
     case('-redef_box')
         call redef_box(arg_pos)
+    case('-slip_plane')
+        call run_slip_plane(arg_pos)
     case default
         print *, 'Option ', trim(adjustl(option)), ' is not currently accepted.'
         stop 3 
diff --git a/src/elements.f90 b/src/elements.f90
index 6df859b..a1ab9bc 100644
--- a/src/elements.f90
+++ b/src/elements.f90
@@ -736,4 +736,24 @@ module elements
 
     end subroutine lattice_map
 
+    subroutine get_interp_pos(i,j,k, ie, r)
+        !This returns the position of an interpolated basis from an element ie.
+        !i, j, k should be in natural coordinates
+
+        integer, intent(in) :: i, j, k, r, s, t, ie, inod -= 
+        real(kind=dp), dimension(3,max_basisnum), intent(out) :: r 
+
+        r = (1.0_dp*(i-1)-(size_ele(ie)-1)/2)/(1.0_dp*(size_ele(ie)-1)/2)
+        s = (1.0_dp*(j-1)-(size_ele(ie)-1)/2)/(1.0_dp*(size_ele(ie)-1)/2)
+        t = (1.0_dp*(k-1)-(size_ele(ie)-1)/2)/(1.0_dp*(size_ele(ie)-1)/2)
+        r(:) = 0
+        do ibasis = 1, bnum
+            do inod = 1, 8
+                r(:,ibasis) = r(:,ibasis) + a_shape(inod) * r_node(:,ibasis,inod,ie)
+            end do
+        end do
+
+
+    end subroutine 
+
 end module elements
diff --git a/src/mode_create.f90 b/src/mode_create.f90
index bcec2d5..00d7d8b 100644
--- a/src/mode_create.f90
+++ b/src/mode_create.f90
@@ -528,7 +528,7 @@ module mode_create
                             do i = 1, 3
                                 filzero(i) = bd_ele_lat(2*i-1) -1
                             end do
-                            do while(efill_size>9)
+                            do while(efill_size>min_efillsize)
                                 !First check whether there are enough lattice points to house the current element size
                                 efill_ele=cubic_cell*(efill_size-1)
                                 if  (nump_ele < efill_size**3) then 
diff --git a/src/parameters.f90 b/src/parameters.f90
index f261552..8677381 100644
--- a/src/parameters.f90
+++ b/src/parameters.f90
@@ -3,7 +3,8 @@ module parameters
     implicit none
 
     !Default precision
-    integer, parameter :: dp= selected_real_kind(15,307)
+    integer, parameter :: dp= selected_real_kind(15,307), &
+                          min_efillsize = 11
     !Parameters for floating point tolerance
     real(kind=dp), parameter :: lim_zero = epsilon(1.0_dp), &
                                 lim_large = huge(1.0_dp), &