anchor.diff:           DO J = I + 1,Natom
    
   ! Calculate the distance between the two atoms
  -            Dx = Rxx(I) - Rxx(J)
  -            Dy = Ryy(I) - Ryy(J)
  +            Dx = Xx(I) - Xx(J)
  +            Dy = Yy(I) - Yy(J)
    
   ! Apply the periodic boundary conditions
               Dx = Dx - Box*nint(Dx/Box)
               Dy = Dy - Box*nint(Dy/Box)
    
               R_square = Dx*Dx + Dy*Dy  
  -! Determine the Lennard-Jones parameters dependent on the two atom types             
  -             Type1 = atom_type(I)   !Array list of atom type
  -             Type2 = atom_type(J)  
  +! Determine the Lennard-Jones parameters dependent on the two atom types          
  +             Type1 = AT(I)   !Array list of atom type
  +             Type2 = AT(J)  
               
                ! Type 1 and 2 will be 1-4 integer of atom type
                Rcut = R_cut_matrix(Type1,Type2)
  
positive.code:  
        Return
        END SUBROUTINE
  
negative.code:                R_square_i = 1.0/R_square
                 sigma_square = sigma**2.0
                 R_six_i = (R_square_i*sigma_square)**3.0
            
                 Upot  = Upot + 4.00*eps*R_six_i*(R_six_i - 1.00) - Ecut
                 Ff    = 48.0*eps*R_square_i*R_six_i*(R_six_i - 0.5)
  
                 Press = Press + Ff
                 Ff    = Ff*R_square_i
  !  Update the total force on atoms
  