Difference between revisions of "Calculating optical spectra including excitonic effects: a step-by-step guide"
| Line 29: | Line 29: | ||
===Step 4: Include previous quasiparticle (GW) results === | ===Step 4: Include previous quasiparticle (GW) results === | ||
Follow the module on '''[[Bethe-Salpeter on top of quasiparticle energies]]''' and '''return to this tutorial''' | Follow the module on '''[[Bethe-Salpeter on top of quasiparticle energies]]''' and '''return to this tutorial''' | ||
==Links== | |||
* Back to [[BSE hBN Yambo Virtual 2021 version|BSE tutorial sections]] | |||
* [[Modules|Back to technical modules menu]] | |||
* [[Tutorials|Back to tutorials menu]] | |||
<!-- | <!-- | ||
| Line 323: | Line 328: | ||
[[File:03 bse diago qp.png|none|600px]] | [[File:03 bse diago qp.png|none|600px]] | ||
It is clear that this makes a difference in the peak distribution and intensity. Note that beside a simple shift you can renormalise as well the bandwidth of the valence and conduction bands in KfnQP_E (respectively the third and second value). You can try as an exercise to set up a new calculation using e.g. 1.440000 | 1.200000 | 0.900000 | for KfnQP_E. | It is clear that this makes a difference in the peak distribution and intensity. Note that beside a simple shift you can renormalise as well the bandwidth of the valence and conduction bands in KfnQP_E (respectively the third and second value). You can try as an exercise to set up a new calculation using e.g. 1.440000 | 1.200000 | 0.900000 | for KfnQP_E. | ||
=References = | =References = | ||
<references /> | <references /> | ||
--> | |||
Revision as of 11:47, 25 March 2021
This tutorial guides you through the workflow of a calculation of the optical spectrum of a given material by solving the Bethe-Salpeter equation. Specifically, we will use bulk h-BN as an example.
Before starting, you need to obtain the tarballs for hBN. See instructions on the main tutorials page.
The target quantity in a Bethe-Salpeter calculation is the macroscopic dielectric matrix εM. The following quantities/steps are needed to obtain εM:
The optical absorption spectrum corresponds to ImεM(ω). Following this scheme we go through the flow of a calculation:
Step 1: Static screening
Use the SAVE folders that are already provided and type:
$ cd YAMBO_TUTORIALS/hBN/YAMBO
Follow the Static screening module and then return to this tutorial
Step 2: Bethe-Salpeter kernel
Follow the module on Bethe-Salpeter kernel and return to this tutorial
Step 3: Diagonalisation of the excitonic Hamiltonian
This is the step in which you obtain the spectra. Mathematically this implies solving a large eigenvalue problem. In this case we are going to directly diagonalise the matrix, but there are different numerical approaches available in Yambo. The difference between the various other approaches and when they should be used is the object of one of the next tutorials.
Follow the module on Bethe-Salpeter solver: diagonalization then return to this tutorial
Step 4: Include previous quasiparticle (GW) results
Follow the module on Bethe-Salpeter on top of quasiparticle energies and return to this tutorial
Links