Bethe-Salpeter

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In this tutorial

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BSE Tutorials at present:

• SiH_4

• Fantastic dimension

• LiF

• you Hydrogen

• GaSb (SOC)

• hexagonal BN (on slides only)

The material

Bulk hexagonal BN [1] hexagonal lattice Two atoms per cell (16 electrons) Lattice constant a = 4.72 [a.u.] c/a= 2.58 Plane waves cutoff 40 Rydberg

Calculate screening

A key ingredient in the construction of the BS kernel in the screeened exchange approximation (sex) is the screened electron-electron interaction W which is commonly evaluated in the static approximation.

Runlevel to be used is yambo -b

Calculate the BS kernel in the SEX (Screened Exchange approximation) in the transition space

Runlevel to be used yambo -o b -k sex

Solve the BSE by haydock solver

Runlevel to be used yambo -y h

Solve the BSE by diagonalizing the excitonic matrix

Runlevel to be used yambo -y d

Steps:

-Calculate screening

-Calculate the BS Kernel

-Diagonalize the BS Matrix and calculate spectrum

-Visualize/Analyze excitons (with ypp)

-How to Converge

-How to work with SOC