anchor.diff:    double precision :: epsilon, sigma, sigma_cut
   
     integer :: i, L(3), seed_size, clock, error
  +  integer :: j
     integer, allocatable :: seed(:)
   
     call random_seed(size = seed_size)
  
positive.code:   type(h5md_file_t) :: datafile
    type(h5md_element_t) :: elem
    type(h5md_element_t) :: e_solvent
    integer(HID_T) :: colloids_group, box_group
  
    integer, parameter :: N = 1000
    integer, parameter :: N_colloids = 3
  
negative.code:      write(12, *) neigh% list(:, i)
    end do
  
    call e_solvent% append(solvent% pos, 0, 0.d0)
  
    do i = 1, 50
       solvent% pos = solvent% pos + 0.1d0
       do j= 1, 3
          solvent% pos(:, j) = modulo( solvent% pos(:, j), L(j)*1.d0 )
       end do
  
       call solvent% sort(solvent_cells)
       call neigh% update_list(colloids, solvent, 1.4d0, solvent_cells)
       call e_solvent% append(solvent% pos, i, i*1.d0)
    end do
  
    call e_solvent% close()
  
    call h5gclose_f(colloids_group, error)
    call h5gclose_f(solvent_group, error)
  
    call datafile% close()
  
    call h5close_f(error)
  
  