# Definition of what an energy band is?

1. May 9, 2009

### lotrsimp12345

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
is this correct?
An energy band is a continuous distribution of similar energy levels?

What is the reason for energy bands in solids?
The reason is there is a close proximity of many atoms which is because the energy difference becomes very small. So the energy is bundled together rather than representing indivual energy levels.

2. May 9, 2009

### nickjer

The last answer sounds odd. Lets say you have a lot of spaced out atoms with discrete energy levels. As they get closer to each other, the wavefunctions will overlap and those discrete energy levels will lose their degeneracy and begin to spread out. As they spread out, you get a range in energy that the electrons can live in, basically a band. So it is due to this periodicity with overlapping wavefunctions that you get bands.

3. May 9, 2009

### nickjer

Hmm... Just realized you double posted this. Please don't post the same question in multiple threads.

4. May 9, 2009

### lotrsimp12345

now my question is how would you know what states the s-band can have?