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This page gives hints on how to compute the matrix elements of the electron-phonon interaction with the ABINIT package.

The theory and details of the implementation are described in [[cite:Gonze2009]] and [[cite:Gonze2016]].

Basic calculations of electron-phonon interaction in ABINIT: one performs a normal ground state, then DFPT phonon calculations (using [[rfphon]], with added keywords [[prepgkk]] and [[prtgkk]], which saves the matrix elements to files suffixed GKK. The main change in this respect is that [[prtgkk]] now disables the use of symmetry in reducing q-points and perturbations. This avoids ambiguities in wave function phases due to band degeneracies. The resulting GKK files are merged using the mrggkk utility, and processed by anaddb.

With the implementation of phonons in PAW DFPT, the electron phonon coupling is also available in PAW, though this has not yet been tested extensively. The input variables for electron-phonon coupling in anaddb are described in [[cite:Gonze2009]] and [[cite:Gonze2016]].

Some details about the calculation of electron-phonon quantities in ABINIT and ANADDB can be found [[pdf:elphon_manual.pdf|here]].

Subsequently, the GKK file is used to compute many quantities, as explained in [[topic:PhononWidth]], [[topic:TDepES]] and [[topic:ElPhonTransport]].

A brand new ABINIT driver, focusing on the treatment of electron-phonon interaction is under development. Most of the input variables for experts, with [[optdriver]]==7 are related to this development, that is not yet operational as of v8.5.

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- [[tutorial:rf1|The tutorial Response-Function 1 (RF1)]] presents the basics of DFPT calculations within ABINIT. The example given is the study of dynamical and dielectric properties of AlAs (an insulator): phonons at Gamma, dielectric constant, Born effective charges, LO-TO splitting, phonons in the whole Brillouin zone. The creation of the “Derivative Data Base” (DDB) is presented.
- [[tutorial:eph|The tutorial on the electron-phonon interaction]] presents the use of the utility MRGKK and ANADDB to examine the electron-phonon interaction and the subsequent calculation of superconductivity temperature (for bulk systems).