Currently I'm trying to understand electronic band structures such as depicted below:
And following questions were arisen.
Why are there multiple lines in valence side and conduction side? Where are the bands and gaps between them starting from the lowest energy (inner electrons) to higher energies (up to valence band and conduction band)? How can I distinguish between them in the pictures like presented above? I just want to see a connection of that picture with the following:
Why do these different lines intersect each other at some points? (Don't they?) What does it mean?
Why do we choose path connecting the points of high symmetry in 1-st Brillouine zone? What's wrong with random directions? Does this path cover all possible energy values of electron in crystal? If so, then how come is that?
Thanks in advance!