Degenerate bands in EPW calculations
Posted: Wed May 29, 2019 4:48 am
Dear EPW developers,
The reference PRB 87, 024505 (2013) says that in the implementation of EPW, the el-ph self-energy is assumed to be diagonal in band indices. Does this approximation break down for systems with multiple-degenerate bands at the Fermi level?
For example, a simple cubic perovskite oxide ABO3, upon electron doping, the Fermi level crosses three degenerate t2g bands of the B ion. In that case, can we still assume that the el-ph self-energy is diagonal in band indices and off-diagonal terms are neglected?
Thank you very much.
Dr. Hanghui Chen
Department of Physics
NYU Shanghai and New York University
The reference PRB 87, 024505 (2013) says that in the implementation of EPW, the el-ph self-energy is assumed to be diagonal in band indices. Does this approximation break down for systems with multiple-degenerate bands at the Fermi level?
For example, a simple cubic perovskite oxide ABO3, upon electron doping, the Fermi level crosses three degenerate t2g bands of the B ion. In that case, can we still assume that the el-ph self-energy is diagonal in band indices and off-diagonal terms are neglected?
Thank you very much.
Dr. Hanghui Chen
Department of Physics
NYU Shanghai and New York University