Analysis of the Condition for the Applicability of Degenerate Perturbation Method

This paper mainly discusses the condition for the applicability of degenerate perturbation method.The exact analytical expression can be obtained in the non-degenerate case,and only the first-order approximate energy correction can be calculated in the degenerate case.However,the conditions for the degenerate perturbation and non-degenerate perturbation are different.In this paper,the method for comparing the energy-level correction and theoretical result in the degenerate case has been obtained by adopting the numerical analysis on two-dimensional the infinite quantum well.