 Half-line square-root potential well

A confining Quantum Hamiltonian on $x>0$ with $a>0$, potential $a\sqrt{x}$ and a Dirichlet boundary condition at zero has natural length $\ell =({\hslash }^2/(2ma){)}^{2/5}$ and energy $E_{\ast }=({\hslash }^2{a}^4/(2m){)}^{1/5}$. Rescaling $x=\ell y$ gives $H/E_{\ast }=-d^2/d{y}^2+\sqrt{y}$, so every energy eigenvalue scales as $E_{\ast }$. The potential derivative diverges at the wall even though the potential itself is finite there.