EPW Forum

Dear EPW Users,

As you are aware, the initial eigenstates (u_nk), the periodic part of the Bloch states, are available from DFT wave functions in the evc.dat files from QE.

Does EPW store (or calculate) the "final" Wannier-interpolated eigenstates in the Bloch representation for the fine or coarse k-grid? I am hoping to use this information to calculate the overlap integral u*_k'(r)u_k(r)dV within EPW which can then be used for calculating impurity scattering rates.

Thank you,

Vahid

Vahid Askarpour
Department of Physics and Atmospheric Science
Dalhousie University,
Halifax, NS, Canada

Dear Vahid,

While the Bloch states on the coarse grid are available from the DFT calculation, EPW doesn't calculate the Wannier-interpolated eigenstates in the Bloch representation on the fine grid - nor does Wannier90 actually. It can be done but it's expensive and generally not required.

Best
Carla

Dear Carla,

Since calculating Bloch states on the fine grid is expensive, to calculate the overlap integral for the periodic part of the Bloch states (u_nk) on the fine grid, can one calculate the overlap integral on the coarse grid (as done in the Wannier90 code by calculating M_mn matrices) and then interpolate M unto the fine grid using the same procedure done for the Hamiltonian and el-ph matrix elements?

Thank you,

Vahid

Dear Vahid,

It can probably be done but it's not trivial if you try and formally invert the formulas in Bloch/Wannier representation for the overlaps of the Bloch states.

Carla