With the development of semiconductor growth technology

people have produced kinds of quantum dots.Due to the novel optoelectronic properties and the transport characteristics of quantum dots

there will be a widely applied prospect for them.Many investigators studied the properties of a quantum dot by means of various theoretical and experimental methods.In recent years

with the study of the properties of bound polaron in a quantum dot

people have paid more attention to them.Woggon

et al

.studied the states of polarons bound in a potential and determined the local optical absorption spectrum up to first-order time-dependent perturbation theory with respect to the electron-phonon interaction.Chen

et al

.derived the expression of the ground state energy of an electron coupled simultaneously with a coulomb potential and a longitudinal-optical phonon field in parabolic quantum dots and wires within the framework of Feynman variational path-integral theory.Xie

et al

.investigated the binding energy of a bound polaron in a spherical quantum dot by using the varia-tional method

and so on.However

few investigators studied the bound polaron in the quantum dot with the linear combination operator method so far.By using the linear combination operator and unitary transformation method

the properties of the bound polaron in a parabolic quantum dot are studied for the strong electron-phonon coupling case.Results show that the vibration frequency of the strong-coupling bound polaron in a parabolic quantum dot will increase strongly with decreasing the effective confinement length of quantum dot and increase with increasing the electron phonon coupling strength.The ground state energy of the strong-coupling bound polaron will increase strongly with decreasing the effective confinement length

and at the same value of the confinement length

the higher the coupling strength

the higher is the value of the ground state energy.The ground state energy of strong-coupling bound polaron change little with electron-phonon coupling strength for

l

0

>

0.30

whereas they change strongly with electron-phonon coupling strength for

l

0

>

0.30.The ground state energy of strong-coupling bound polaron will increase with increasing the coulomb bound potential.From the equation of the effective confinement length of the quantum dot

l

0

=√

E/mω

0

we can see that the effective confinement length of quantum dot is reciprocal with the square root of the confinement strength ω

0

of the quantum dot.Thus the vibration frequency and the ground state energy of strong-coupling bound polaron in a parabolic quantum dot will increase with increasing the confinement strength.