Time-dep perturbation theory

1. Nov 16, 2007

omyojj

while Im reading the griffiths textbook..

got my curiosity from "Typically, the diagonal matrix elements of H vanish"

i.e. <a|H|a>=0 in general..

If V(x) does not have an angular dependence..

the selection rule implies <a|H|a>=0 (since Δl=0)..yes..

but what if it does?

what it(vanishing diagonal element of H) means
physically (in view of the perturbation theory)