Let $B$ be a magnetic field, let $\mathbf{a}$ be a vector and let $\Psi$ be the wave function. If $\mathcal{H}(B) = (-i\nabla + B\mathbf{a})^2$, where $\nabla$ is the gradient, then the time-independent magnetic Schrodinger equation is given by
$$\mathcal{H}(B) \Psi = \lambda \Psi$$
What is a simple way of finding the eigenvalue and eigenfunction solution to the above equation?