Sorry if the title is misleading.
I am trying to obtain $V(r)$ from the following equation:
$\frac{\partial^2}{\partial t^2} C(r,t) = (-\frac{\partial^2}{\partial r^2} + V(r))^2 C(r,t)$
I can do this when $(-\frac{\partial^2}{\partial r^2} + V(r))$ is not squared but alas it is squared.
I am wondering if there are any neat ways of dealing with such equations. If I expand $(-\frac{\partial^2}{\partial r^2} + V(r))^2$ it doesn't get me anywhere. Have done some research but only helps me when $V(r)$ is a constant.
Any help would be appreciated.