First order peturbation theory.

[wgdtelr]

Homework Statement

A particle of mass m and spin 1/2 is moving in an infinite, symmetric potential well
V (x) = { 0 -L<= x <= L.
= ∞ otherwise..

Under the effect of a weak external magnetic field.
B = -B k^ ; -L <= x <= 0
= -B i^ 0 <= x <= L.
where i^ and k^ are the unit vectors along the Ox and Oz directions. Calculate, in the first order of perturbation theory, the energy of the nth exited state of the partic

The Attempt at a Solution

give me some hints to start this problem.

 

[Born2bwire]

The energy calculation is fairly straightforward, do you know what the relevant equation is? As for the process, you need to first define what the perturbed Hamiltonian is and the unperturbed eigenstates are.