In my course notes for atomic physics, looking at time independent perturbation for the non-degenerate case, we have the following:(adsbygoogle = window.adsbygoogle || []).push({});

http://i.imgur.com/ao4ughk.png

However I am confused about the equation 5.1.6. We know that < phi n | phi m > = 0 for n =/= m, so shouldn't this mean that < phi n | V | phi m > = 0 as well? Would someone be able to explain why this is not the case? I feel like I must be missing some important aspect of Dirac notation here.

Thanks

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# Time independent perturbation theory

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