  Lattice effects on photo-excited states in interacting charge frustrated
system are examined. Real time dynamics in the interacting spinless fermion
model on a triangular lattice coupled to lattice vibration are analyzed by
applying the exact diagonalization method combined with the classical equation
of motion. A photo-induced phase transition from the horizontal stripe-type
charge order (CO) to the 3-fold CO occurs through a characteristic intermediate
time domain. By analyzing the time evolution in detail, we find that this
characteristic dynamics are seen when the electron and lattice sectors are not
complementary to each other but show cooperative time evolutions. We also find
that there are threshold values in the optical fluorescence and
electron-lattice coupling for emergence of the photo-induced 3-fold CO. The
dynamics are distinct from those from the vertical stripe-type CO, in which a
monotonic CO melting occurs. A scenario of the photo-induced CO phase
transition with lattice degree of freedom is presented from a view point of
charge frustration.
