Theoretical studies on the recently observed optically induced magnetizatio
n in nanoparticles of K0.2Co1.4[Fe(CN)(6)]. 6.9H(2)O have been carried out
by simulating the solid with representative clusters. Our studies, performe
d within the density-functional formalism, show that the ground state is su
pplemented by several excited states with varying spin multiplicities. Illu
mination of the solid by light results in excitations to different states d
epending on the photon energy. In particular, it is shown that while red li
ght enhances the magnetization, blue light reduces it-in agreement with the
observed changes. [S0163-1829(98)04846-2].