anchor.diff:       if (solvent% pos(2,m) < (L(2)/2.d0)) then
           solvent% species(m) = 1
        else
  -        solvent% species(m) = 2
  +        solvent% species(m) = 3
        end if
     end do
   
  
positive.code:   sigma(2,2) = 2*sigma_N
    sigma_cut = sigma*2**(1.d0/6.d0)
  
    call colloid_lj% init(epsilon, sigma, sigma_cut)
  
    epsilon(1,1) = 1.d0 
    epsilon(1,2) = 1.d0 
  
negative.code:   integer :: error
  
    double precision :: sigma_N, sigma_C, max_cut
    double precision :: epsilon(3,2)
    double precision :: sigma(3,2), sigma_cut(3,2)
    double precision :: mass(2)
  
    double precision :: v_com(3), wall_v(3,2), wall_t(2)
  