Abstract
The authors derive an exact sum rule satisfied by the dispersion relations of the commensurable case of Harper's equation (1955). They use this result to derive a lower bound for the total bandwidth of the spectrum and to provide a stronger analytical justification for a result due to Thouless (1990) concerning the total bandwidth when the commensurability is a high order rational.
| Original language | English |
|---|---|
| Article number | 033 |
| Pages (from-to) | 6123-6133 |
| Number of pages | 11 |
| Journal | Journal of Physics A: Mathematical and General |
| Volume | 25 |
| Issue number | 22 |
| DOIs | |
| State | Published - 1992 |
| Externally published | Yes |