# PhononWidth

This page gives hints on how to compute the linewidth (or lifetime) of phonons, due to the electron-phonon interaction with the ABINIT package.

## Introduction¶

This topic concerns metals only.

After generating a GKK file (see topic_ElPhonInt), the Electron-Phonon Coupling (EPC) analysis is performed in anaddb, setting elphflag variable to 1. Most of the procedure is automatic, but can be lengthy if a large number of k-points is being used. The nqpath and qpath variables must be set, specifying a path in reciprocal space. anaddb generates files containing the phonon linewidths (suffixed _LWD) and frequencies ωqj (suffixed _BST) along qpath. One can calculate the nesting function n(q) = ∑kii’ δ(εk,i) δ(εk+q,i’) by setting prtnest to 1 (output to _NEST).

compulsory:

basic:

• kptrlatt K PoinT Reciprocal LATTice
• nqpath Number of Q wavevectors defining a PATH
• qpath Q wavevectors defining a PATH
• telphint Technique for ELectron-PHonon INTegration

useful:

• ep_int_gkk Electron-Phonon INTerpolation of GKK
• ep_qptlist Electron Phonon Q PoinT LIST
• ep_scalprod DO SCALar PRODuct for gkk matrix elements
• ndivsm Number of DIVisions for the SMallest segment
• prtnest PRinT the NESTing function
• prtvol PRinT VOLume

expert:

tutorespfn:

v5:

v6:

v7:

## Tutorials¶

• 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).