Dear all;
I always met such cases, the GW gap is smaller than the BS energy, that means the binding energy is minus, in some case, I strength the K sampling and the problem solved, but in many other cases, it didn't work, well, could anyone give some advice on this issue? how to determine a system whether can bind exciton or not? Thanks
Xi Zhu
Nanyang University
Singapore,639798
no bound exciton
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Re: no bound exciton
The fact that the GW gap is smaller that the lowest BS energy is not a problem, in general. There is no strict, exact rule to determine whether your system is gonna have a bound exciton. So, please, give us more details about your system: is it a metal, a semicondutor or an insulator. How large is the DFT/GW gap ? Home many atoms, which type of atoms .... and so on.xixi wrote:Dear all;
I always met such cases, the GW gap is smaller than the BS energy, that means the binding energy is minus, in some case, I strength the K sampling and the problem solved, but in many other cases, it didn't work, well, could anyone give some advice on this issue? how to determine a system whether can bind exciton or not? Thanks
From a very very general point of view you could say
- larger the gap, larger the probability to have a bound exciton
- larger the dis-homogeneity, larger the probability to have a bound exciton
- metal = no bound excitons
- ...
Andrea
Andrea MARINI
Istituto di Struttura della Materia, CNR, (Italy)
Istituto di Struttura della Materia, CNR, (Italy)