Here we present a microscopic theory to explain different Raman phonon
modes of the cuprates in normal state. We used the electronic Hamilto
nian of Fulde in presence of anti-ferromagnetism. We added phonon inte
raction to the hybridisation between the conduction electrons of the s
ystem and the f-electrons. The spectral density is calculated by the G
reen function technique of Zubarev at zero wave vector and low tempera
ture limit. The spectral density is studied in detail by varying model
parameters like position of f-level (epsilon(f)), the effective elect
ron-phonon coupling strength (g), the staggered magnetic field (h) and
the hybridisation parameter (V). Four Raman active modes are observed
in addition to the original phonon peak. Then their softening and har
dening behaviour and change in peak height are studied, These paramete
rs influence the Raman modes substantially. (C) 1998 Elsevier Science
Ltd. All rights reserved.