We present a theoretical methodology to study the electronic response prope
rties of a chromophore physisorbed on a metal particle. In particular the c
hromophore is treated at ab initio level whereas the metal particle is desc
ribed through its dielectric properties. The use of a boundary elements met
hod for the resolution of the electrostatic problem allows the study of par
ticles with complex shapes. The theoretical procedure is applied to the stu
dy of different quantities such as the chromophore effective polarizability
, the UV-VIS absorption of the chromophore coated metal particle, and the s
urface enhanced Raman scattering (SERS) of the physisorbed molecule for two
reliable chromophores (merocyanine dyes) physisorbed on copper and silver
metal particles of various sizes and shapes. (C) 2001 American Institute of
Physics.