polar 2d materials

[nprot]

Hi,

QE/EPW currently does not use a truncated Coulomb potential for treating 2d materials. As such, is it correct to use the flag lpolar for the calculation of self-energies for polar 2d materials? I find that when lpolar is true for monolayer MoS2, the electronic scattering rates come out to be three orders of magnitude higher than published results in literature. Setting lpolar to false gives reasonable results.

On a related note, I found that the flag system_2d does not make any difference to the result.

Best regards

[sponce]

Dear nprot,

It is correct, there are no Coulomb truncations at the moment.

You have to use the polar flag otherwise the Wannier interpolation will be very wrong close to the zone center.

The flag system_2d is indeed inactive at the moment for that part of the code.

What you would have to do at the moment is to increase the vacuum layer until convergence (this can be very large due to the 1/r interaction between replicas).

Best,
Samuel

[nprot]

Thank you.