anchor.diff:    solvent% species = 1
   
     call solvent_cells%init(L, 1.d0)
  -
  +  colloids% pos(:,1) = solvent_cells% edges
  +  
     call solvent% random_placement(solvent_cells% edges, colloids, solvent_colloid_lj)
   
     call solvent% sort(solvent_cells)
  
positive.code:   write(*,*) '    e co so     |   e co co     |   kin co      |   kin so      |   total       |   temp        |'
    write(*,*) ''
  
    do i = 1, 100
       so_max = 0
       co_max = 0
       md: do j = 1, N_MD_steps
  
negative.code:   call colloid_lj% init( reshape( [ epsilon ], [1, 1] ), &
         reshape( [ sigma ], [1, 1] ), reshape( [ sigma_cut ], [1, 1] ) )
  
    mass = rho * sigma**3 * 4 * 3.141/3
    write(*,*) 'mass =', mass
  
    call solvent% init(N)
  
    call colloids% init(1)
    
    open(15,file ='data14.txt')
    
    write(*, *) colloids% pos
    colloids% species = 1
    colloids% vel = 0
    
    call random_number(solvent% vel(:, :))
    solvent% vel = (solvent% vel - 0.5d0)*sqrt(6.d0*2)
    solvent% vel = solvent% vel - spread(sum(solvent% vel, dim=2)/solvent% Nmax, 2, solvent% Nmax)
  