Low-lying States And Symmetry Effect Of Two-dimensional Negatively Charged Exciton

For study the complicated many-body system,it is useful to deeply understand the few-body system.As the simplest few-body system,three-body systems attracted many attentions,not only theoretical,but also experimental.We studied the negatively charged exciton system trapped by a 2D parabolic potential as an example.We calculated the energy,analysed the size effect and symmetry effect,then theoretically verified the results.In chapter 1,research of few-body system and symmetry effect,as well as introduction of exciton are briefly introduced.In chapter 2,we introduced the product base of harmonic oscillator,and deduced the Talmi-Moshinsky transformation bracket of 2D N-body and three-body system,respec-tively.In chapter 3,we studied a negatively charged exciton(NEC),which is trapped by a 2D parabolic potential.By using matrix diagonalization techniques,the correlation energies of the low-lying states are calculated as a function of confinement strength.The size effect of different states is different,which can be explained as a hidden symmetry.It is also found that the confinement may cause accidental degeneracies and crossing between levels with different low-excited states.In chapter 4,the binding energies of the lowest singlet and triplet states of NEC confined to a 2D parabolic potential are studied using exact diagonalization techniques. We investigated the dependence of binding energies of the ground state and the first excited bound state on the confinement strength and on the effective electron-to-hole mass ratio.The results we have obtained show that the binding energies are closely correlated to the strength of the confinement potential and the effective electron-to-hole mass ratio.Chapter 5 is summary of the whole paper.