Added keyword for group selection based on nodal position instead of centroid

src/opt_group.f90

@@ -11,7 +11,7 @@ module opt_group
     integer :: group_ele_num, group_atom_num, remesh_size,normal, dim1, dim2
     character(len=15) :: type, shape !Type indicates what element type is selected and shape is the group shape
     real(kind=dp) :: block_bd(6), centroid(3), vertices(3,3),disp_vec(3), tip_radius, bwidth
-    logical :: displace, delete, max_remesh, refine
+    logical :: displace, delete, max_remesh, refine, group_nodes
 
     integer, allocatable :: element_index(:), atom_index(:) 
 
@@ -334,6 +334,8 @@ module opt_group
                 max_remesh =.true.
             case('delete')
                 delete=.true.
+            case('nodes')
+                group_nodes=.true.
             case default
                 !If it isn't an available option to opt_disl then we just exit
                 exit 
@@ -363,6 +365,7 @@ module opt_group
         !Check the type to see whether we need to find the elements within the group
         select case(trim(adjustl(type)))
         case('elements', 'both')
+            if(.not.(group_nodes)) then 
                 do i = 1, ele_num
                     r_center(:) = 0.0_dp
                     do inod = 1, ng_node(lat_ele(i))
@@ -383,8 +386,27 @@ module opt_group
                         element_index(group_ele_num) = i
                     end if 
                 end do 
+            else if(group_nodes) then 
+                eleloop:do i = 1, ele_num
+                    r_center(:) = 0.0_dp
+                    do inod = 1, ng_node(lat_ele(i))
+                        do ibasis = 1, basisnum(lat_ele(i))
+                             if (in_group(r_node(:,ibasis,inod,i))) then 
+                                group_ele_num  = group_ele_num + 1
+                                if(group_ele_num > size(element_index)) then
+                                    allocate(resize_array(size(element_index) + 1024))
+                                    resize_array(1:group_ele_num-1) = element_index
+                                    resize_array(group_ele_num:) = 0
+                                    call move_alloc(resize_array, element_index)
+                                end if
+                                element_index(group_ele_num) = i
+                                cycle eleloop
+                            end if 
+                        end do
+                    end do
+                end do eleloop
+            end if
         end select
-
                 !Check the type to see if we need to find the atoms within the group
         select case(trim(adjustl(type)))
         case('atoms','both')