Abstract: The methods for fewbody physics are introduced to investigate the lowlying energy spectra of a barrier spinunpolarized Li quantum dot (QD) under an arbitrary strength in a magnetic field. A twodimensional threeelectron QD bound by a positive impurity, which is located on the zaxis at a distance d from the QD plane (the xy plane), is called a barrier Li QD. When electron spins were unpolarized, the dependence of the lowlying energy of the barrier Li QD on an external magnetic field B and the distance d was obtained. The angular momentum L of the lowest state is found to jump not only with the variation of B but also with that of d. Then these results were analyzed by using dynamics.

Key words: quantum dots, magnetic fields, impurity, energy spectra