SUBROUTINE LJ_Potential(r,v,vp,vpp,sigma,depth)
   USE Numeric_Kinds_Module
   IMPLICIT NONE
   REAL(KIND=wp_kind), PARAMETER :: Four=4.d0
   REAL(KIND=wp_kind) r, v, vp, vpp, sigma, depth
   
   IF((r/sigma)**12<1.d-10)THEN
     v=500
     vp=-500
     vpp=500
     RETURN
   ENDIF
   
   v=Four*Depth*((sigma/r)**12-(sigma/r)**6)
   vp=Four*Depth*(-12*(sigma/r)**13+6*(sigma/r)**7)/sigma
   vpp=Four*Depth*(12*13*(sigma/r)**14-6*7*(sigma/r)**8)/sigma**2
   
   RETURN
ENDSUBROUTINE LJ_Potential