[Pw_forum] Ewald and Coulomb

[jiayudai]

Dear users and developers,

Happy new year!

I have a confusion about the calculations of ion-ion interactions. We know, we usually use Ewald scheme to represent the real Coulomb potentials in a periodic cell. Generally, it is correct for a neutral system or one electron taken out (or into ) system. However, if the system is constructed with partially charged ions, that is to say, there are more positive charges than negative charges, the Ewald scheme should be not right. Although this system is not stable, but there should be some properties deserved to study.

So, how can we calculate the true Coulomb potentials in DFT? That is to say, we do not use Ewald, but only use th 1/r type. I know it can be realized in classical calculations, but i did not find the path to get it in QE.

Thanks a lot.

Jiayu


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Jiayu Dai
Department of PhysicsNational University of Defense Technology, 
Changsha, 410073, P R China
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