Difference between revisions of "Calculating optical spectra including excitonic effects: a step-by-step guide"
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Follow the module on '''[[Bethe-Salpeter kernel]]''' and '''return to this tutorial''' | Follow the module on '''[[Bethe-Salpeter kernel]]''' and '''return to this tutorial''' | ||
===Step 3: | ===Step 3: Diagonalisation of the excitonic Hamiltonian === | ||
This is the final step in which you finally obtained the spectra. | This is the final step in which you finally obtained the spectra. | ||
Mathematically this implies to solve a large eigenvalue problem. | Mathematically this implies to solve a large eigenvalue problem. | ||
'''Part that should be moved to solvers tutorial''' | |||
Two main solvers are available in yambo | Two main solvers are available in yambo | ||
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For (1) follow the module on '''[[Bethe-Salpeter solver: diagonalization]]''' then either '''return to this tutorial''' | For (1) follow the module on '''[[Bethe-Salpeter solver: diagonalization]]''' then either '''return to this tutorial''' | ||
or follow the link to '''[[Bethe-Salpeter solver: Lanczos-Haydock]]''' for (2). | or follow the link to '''[[Bethe-Salpeter solver: Lanczos-Haydock]]''' for (2). | ||
'''End part that should be moved to solvers tutorial ''' | |||
===Step 4: Include previous quasiparticle (GW) results === | |||
Follow the module on '''[[Including quasiparticle database]]'''and '''return to this tutorial''' | |||
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Revision as of 09:40, 16 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 do:
$ 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 final step in which you finally obtained the spectra. Mathematically this implies to solve a large eigenvalue problem.
Part that should be moved to solvers tutorial Two main solvers are available in yambo
(1) diagonalization of the full Hamiltonian (diagonalization solver)
(2) subspace iterative | Lanczos algorithm which by-pass diagonalization with the Haydock approach[1] (Lanczos-Haydock solver)
For (1) follow the module on Bethe-Salpeter solver: diagonalization then either return to this tutorial or follow the link to Bethe-Salpeter solver: Lanczos-Haydock for (2). End part that should be moved to solvers tutorial
Step 4: Include previous quasiparticle (GW) results
Follow the module on Including quasiparticle databaseand return to this tutorial
References
- ↑ R. Haydock, in Solid State Phys., 35 215 (1980) edited by H. Ehrenfest, F. Seitz, and D. Turnbull, Academic Press