Guided Self-assembly (Square)

    The following figure shows a time sequence of a simulation.  The initial condition at t = 0 comprises a background concentration 0.4 and six stripes of concentration 0.8.  As time goes on, the pattern evolves, but is clearly influenced by the initial conditions.  The size of the dots are noticeably nonuniform, but is still of the same scale as previous calculation.  Within the time scale shown here, the dots do not order into a triangular lattice.  Simulation is stopped at t=1000t, although the pattern can still evolve.  It maybe possible to “freeze” and keep these intermediate structures (such as decrease the temperature).  When a pattern at a coarse scale is introduced, e.g., by the photolithography, the coarse pattern acts like a framework, which influences the self-assembles at a fine scale.  Diverse patterns can be produced this way.