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PhononBands

This page gives hints on how to compute phonon bands, density of states, interatomic force constants, sound velocity … with the ABINIT package.

Introduction

The Fourier transformation of the phonon dynamical matrices generates interatomic force constants in real space, as explained in [Gonze1997a]. Backtransforming to reciprocal space gives the Fourier interpolation of the initial phonon band structure. After such Fourier interpolation, the DOS can be produced (see [Lee1995]), the phonon eigenenergies plotted along lines, the slope of the energy versus cristalline momentum evaluated (to give sound velocity).

The two-phonon sum and difference spectra can also be obtained, see dossum.

For the related computation of temperature-dependent properties, see topic_Temperature.

Related Input Variables

compulsory:

• ifcflag Interatomic Force Constants FLAG

basic:

• asr Acoustic Sum Rule
• atifc AToms for IFC analysis
• dipdip DIPole-DIPole interaction
• dossum DOS SUM
• ndivsm Number of DIVisions for the SMallest segment
• ngqpt Number of Grids points for Q PoinTs
• nph1l Number of PHonons in List 1
• nph2l Number of PHonons in List 2
• nqpath Number of Q wavevectors defining a PATH
• prtdos PRinT the phonon Density Of States
• qpath Q wavevectors defining a PATH
• qph1l Q for PHonon List 1
• qph2l PHonon List 2

useful:

• brav BRAVais
• dosdeltae DOS DELTA in Energy
• dossmear DOS SMEARing value
• dostol DOS TOLerance
• eivec EIgenVECtors
• enunit ENergy UNITs
• iatprj_bs Indices of the AToms for the PRoJection of the phonon Band Structure
• ifcana IFC ANAlysis
• ifcout IFC OUTput
• natifc Number of AToms for IFC analysis
• natprj_bs Number of AToms for PRoJection of the Band Structure
• ng2qpt Number of Grids points for Q PoinTs (grid 2)
• nqshft Number of Q SHiFTs
• nsphere Number of atoms in SPHERe
• nwchan Number of Widths of CHANnels
• prt_ifc PRinT the Interatomic Force Constants
• prtddb PRinT the Derivative DataBase files
• prtphbands PRinT PHonon BANDS
• prtsrlr PRinT the Short-Range/Long-Range decomposition of phonon FREQuencies
• prtvol PRinT VOLume
• q1shft Q shifts for the grid number 1
• q2shft Q points SHiFTs for the grids 2
• rifcsph Radius of the Interatomic Force Constant SPHere
• symdynmat SYMmetrize the DYNamical MATrix
• vs_qrad_tolkms Speed of Sound Q-radius, TOLerance KiloMeter/Second

expert:

• freeze_displ FREEZE DISPLacement of phonons into supercells
• nchan Number of CHANnels
• ngrids Number of GRIDS
• outboltztrap OUTput files for BOLTZTRAP code
• outscphon OUTput files for Self Consistent PHONons
• prtbltztrp PRinT input files for BoLTZTRaP code.
• qrefine Q-point REFINEment order (experimental)

Selected Input Files

v2:

• tests/v2/Input/t15.in
• tests/v2/Input/t16.in
• tests/v2/Input/t17.in
• tests/v2/Input/t19.in
• tests/v2/Input/t20.in
• tests/v2/Input/t22.in
• tests/v2/Input/t25.in
• tests/v2/Input/t28.in
• tests/v2/Input/t29.in
• tests/v2/Input/t32.in
• tests/v2/Input/t39.in

v5:

• tests/v5/Input/t95.in

v6:

• tests/v6/Input/t76.in

Tutorials

• The lesson Response-Function 2 (RF2) presents the analysis of the DDBs that have been introduced in the rf1 lesson. The computation of the interatomic forces and the computation of thermodynamical properties is an outcome of this lesson.