q points

This page gives hints on how to set parameters related to the phonon wavevectors (q-points) in DFPT calculations with the ABINIT package.

Introduction

Like the electronic wavefunctions, the collective atomic displacements that are eigenmodes of the corresponding periodic Hamiltonian can be characterized by a wavevector, denoted q-point.

In ABINIT, DFPT calculations for one dataset are done for one specific q-point, that must be specified. In the simplest case, the user gives the corresponding q-point for each dataset, setting nqpt=1 and specifying the corresponding single qpt. However, very often, it is needed to run calculations for dozens or hundreds of q-points. Hence, the following mechanism has been set: the use can specify a set of q points, using input variables similar to the k-points, and then, for each dataset, the number of the q-point in the set is indicated thanks to iqpt. This applies to the generation of q-point grids as well as to q-point paths to produce phonon band structures.

The input variables for specifying q-points in ANADDB are specified in topic_Phonons and topic_PhononBands.

Related Input Variables

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Selected Input Files

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