Bethe-Salpeter kernel

Prerequisites

Run Initialization

Run Static screening

Run GW in PPA

Create the input

$ yambo -F 03_bse_Ws.in -b -o b -k sex -V QP   (for a 3D)

or

$ yambo -F 03_bse_Ws_2D.in -b -o b -k sex -V QP -r (for a 2D)

Open it and change some of the input variables

 BSENGexx=  30 Ry    # [BSK] Exchange components
 BSENGBlk=  2 Ry    # [BSK] Screened interaction block size

In the excitonic hamiltonian the GW energies are required. If you have already generated a ndb.QP database you can read it

KfnQPdb= " E < ./SAVE/ndb.QP "              # [EXTQP BSK BSS] Database

or you can give the numerical value of the GW scissor and conduction and valence streaching.

For hBN bulk put:

 % KfnQP_E
 1.00000 | 1.000000 | 1.000000 |        # [EXTQP BSK BSS] E parameters  (c/v) eV|adim|adim

For hBN-2D put:

 % KfnQP_E
 1.00000 | 1.000000 | 1.000000 |        # [EXTQP BSK BSS] E parameters  (c/v) eV|adim|adim

Close in input and run the code

$ yambo -F 03_bse_Ws.in  ( for 3D)

or

$ yambo -F 03_bse_Ws_2D.in (for 2D)