EPW Forum

Dear experts,

Since the code includes no dynamical effects, i like to know whether inclusion of dynamical effects at many-body perturbation level (GW) increase or decrease the electronic band gap ?
Or is this just system dependent ?

Best wishes
LUCA

Dear LUCA,

To my knowledge there are no formal proof of this but it is observed to usually increase the electron-phonon coupling strength. The renormalization will be stronger and therefore the gap will close more with increasing temperature (in standard semiconductors).

For the case of diamond for example, DFT level gives you a closing of the gap of 0.4 eV at 0K (zero-point motion renormalization) and this becomes 0.6 eV with GW: http://journals.aps.org/prl/abstract/10 ... 112.215501

Hope this helps,

Samuel