  In this study, we examine the dynamics of a one-dimensional Frenkel-Kontorova
chain consisting of nanosize clusters (the ''particles'') and photochromic
molecules (the ''bonds''), and being subjected to a periodic substrate
potential. Whether the whole chain should be running or be locked depends on
both the frequency and the wavelength of the light (keeping the other
parameters fixed), as observed through numerical simulation. In the locked
state, the particles are bound at the bottom of the external potential and
vibrate backwards and forwards at a constant amplitude. In the running state,
the initially fed energy is transformed into directed motion as a whole. It is
of interest to note that the driving energy is introduced to the system by the
irradiation of light, and the driven mechanism is based on the dynamical
competition between the inherent lengths of the moving object (the chain) and
the supporting carrier (the isotropic surface). However, the most important is
that the light-induced conformational changes of the chromophore lead to the
time-and-space dependence of the rest lengths of the bonds.
