sliding with AFM tip

Dear users,

I have been trying to move my graphene group with AFM tip using fix
spring command. Actually, I can not use fix smd command because my
executable is a little bit old. Also, I am not permitted to have a new
executable right now. I do not to need put an exact AFM tip attached
to graphene group. I just to need to pull graphene group with a
certain load under certain value of K spring.

When I use the in file, no movement occurs for the group attached to AFM tip.

I am deeply appreciate any comment.