Now that I am a working professional, I am reviewing the acoustic theory I learned in college. The previous post is here.

If the potential is short-ranged, a large number of reciprocal lattice vectors are required to describe it. This makes the size of the secular equation to be solved correspondingly large. The ...

We have Maxwell s equations for time-varying fields in point form and integral form as follows: From these four equations the wave motion can be inferred. And we might guess (correctly) from the above ...