Phonon-Broadened Optical Spectra: Urbach's Rule
Abstract
Starting from Frölich's Hamiltonian for conduction-electron-optical-phonon interactions, an approximate Green's function G(p, t) is derived. The spectral density derived from this Green's function is shown to possess an exponential tail at low energies, Eω0<<0. This demonstrates that Urbach's rule can be derived from Frölich's Hamiltonian. The approximate Green's function G(p, t) is shown to be related to the intermediate-coupling models for polarons.
- Publication:
-
Physical Review
- Pub Date:
- May 1966
- DOI:
- 10.1103/PhysRev.145.602
- Bibcode:
- 1966PhRv..145..602M