Aquantum dot(QD) consists of an artificial structure in which electrons are confined in all three spatial dimensions and thus has a fully quantized energy spectrum.Aset of electrons held in such a structure is similar to a set of atomic electrons bound to a nucleus

and for this reason QDs are sometimes termed "artificial atoms".Optical and electric properties of QDs structures recently have attracted much attention because of their application potential.These properties are closely related to excitonic states and their coupling with optical phonon modes.There has been a considerable amount of work on the properties of excitons in different QD structures experimentally and theoreti-cally.The purpose of the present work is to investigate the polaron effects on the magneto-exciton in assembled QDs

and to describe a calculation of the Coulomb interaction with a simple perturbation theory.It was shown that

the interaction of the charged particles with bulk longitudinal optical phonons(LO-phonons) is primary and first important.So in this work we restrict ourselves to examine the interaction of electron and hole with bulk LO-phonons only.We write down the Hamiltonian of the exciton-phonon system in QDs with an external magnetic field

and obtain the energy levels of the system by using a developed LLPmethod.The results show that the polaron effects on the magneto-exciton are to lower the energy levels

but the decrements are small.