The spin chain systems with one-dimensional magnetic ordering are promising candidates for
quantum optical devices. This paper shows how the optical excitation can induce various phonon modes in
an ideal Cu-O chain at various lengths. The calculation was carried out at different level theories including
configuration interaction singles for excited states, density functional theory and second-order M??ller-
Plesset perturbation. In general, the number of modes increases with chain length due to growing asymmetry
of atomic positions when chain exceeds 5 nm. There were, however, only two basic modes: one is associated
with the symmetric oscillation of oxygen and another with the asymmetric motion of the same along the
chain. At the length below 4.3 nm, the Raman activity of the symmetric mode (440 cm-1) dominates. From
analysis of density of states, this mode may be associated with the excitation across the lowest LUMO bands
with changing in spin state. ?? 2009 Elsevier B.V. All rights reserved.
