# Yambo Post Processing (ypp)

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YPP is a post-processing tool included in the Yambo distribution.

In this tutorial we present a non-exhaustive list of the things that can be calculated with this tool.

- Brillouin Zone:

-k p→ write the k-point list in different format-k q→ write the q-point list in different format-k s→ generate shifted k-points grid-k h→ write the highest symmetry points in the BZ-k r→ generate random k-points in the BZ-k e→ generate regular k-points grids-map→ map a fine grid of k-points on the coarse one, see Double-grid in Yambo

- Convertions:

-y→ Remove symmetries not consistent with an external perturbation, see Real Time propagation with Yambo and Linear response in real-time-qpdb g→ generate-modify quasi-particle(QP) database-qpdb m→ merge quasi-particle(QP) databases-qpdb e→ expand quasi-particle(QP) database in the full Brillouin zone(BZ)

- Plots:

-b→ Select the momentum of the exciton you want to analize (default = 1)-s w→ Plot electron wave-functions-s d→ Plot electron density-s s→ Plot electron density of states-s m→ Plot electron magnetization-s b→ Interpolate electronic bands using the approach of Ref.^{[1]}, adding-V qpincludes the quasi-particle correction-s c→ Plot the current density

-e s→ Sort exciton according to their energy and dipole, see How to analyze excitons-e sp→ Plot exciton spin-e a→ Write exciton coefficients amplitudes-e w→ Plot excitonic wave-function for fixed hole position, see How to analyze excitons-e i→ Interpolate excitonic dispersion^{[1]}, requires BSE for all q-points, see How to analyze excitons-dipoles exc→ Print excitonic dipoles, see How to analyze excitons-dipoles ip→ Print Kohn-Sham dipole matrix elements-freehole→ Plot excitonic wave-function with free hole position-avehole→ Plot excitonic wave-function with average hole/electron wavefunction, see How to analyze excitons

- SOC:

-soc→ Perturbative SOC mapping

Special features in **ypp_ph**:

-g g→ Read GKKP databases from QuantumEspresso, see Electron phonon coupling-g d→ Read double-grid for phonons, see Electron phonon coupling-g p→ Plot the module of the gkkp matrix elements

-p d→ Phonon density of states-p e→ Electronic Eliashberg functions, see Electron phonon coupling

-e e→ Excitonic Eliashberg functions, see Optical properties at finite temperature-e g→ Exciton-phonon matrix elements (only diagonal part)-e p→ Phonon-assisted excitonic density of state, Optical properties at finite temperature

Special features in **ypp_nl**:

-u→ Analise the non-linear response, see Non-linear spectroscopy

## References

- ↑
^{1.0}^{1.1}Warren E. Pickett, Henry Krakauer, and Philip B. Allen PRB 38 p2721 (1988)