Skip to content

Susceptibility

This page gives hints on how to compute the frequency-dependent susceptibility matrix, and related screened interaction matrix, and inverse dielectric marix with the ABINIT package.

Introduction

In the independent-particle approximation, the frequency-dependent susceptibility matrix, and related screened interaction matrix, and inverse dielectric matrix can be computed.

This can be done on top of eigenfunctions and eigenvalues obtained from Kohn- Sham, generalized Kohn-Sham (e.g. hybrid functionals), as well as self- consistent quasiparticle methodology in the (generalized) Kohn-Sham basis.

This is a prerequisite to many-body perturbation theory calculations, see topic_GW and topic_BSE, to which we refer.

The frequency meshes, used e.g. for integration along the real and imaginary axes, on which the susceptibility matrices (and related matrices) have to be computed are described in topic_FrequencyMeshMBPT.

compulsory:

  • ecuteps Energy CUT-off for EPSilon (the dielectric matrix)
  • ecutwfn Energy CUT-off for WaveFunctioNs
  • optdriver OPTions for the DRIVER

basic:

  • gw_icutcoul GW CUT-off for COULomb interaction
  • gwpara GW PARAllelization level
  • nband Number of BANDs
  • nomegasf Number of OMEGA to evaluate the Spectral Function
  • rcut Radius of the CUT-off for coulomb interaction
  • vcutgeo V (potential) CUT-off GEOmetry

useful:

  • awtr evaluate the Adler-Wiser expression of \chi^{0}_{KS} assuming Time-Reversal
  • getqps GET QuasiParticle Structure
  • gwencomp GW ENergy for COMPleteness
  • irdqps Integer that governs the ReaDing of QuasiParticle Structure
  • mbpt_sciss Many Body Perturbation Theory SCISSor operator
  • nbandkss Number of BANDs in the KSS file
  • nqptdm Number of Q-PoinTs for the Dielectric Matrix
  • qptdm Q-PoinTs for the Dielectric Matrix
  • spbroad SPectral BROADening
  • spmeth SPectral METHod

expert:

  • fftgw FFT for GW calculation
  • gw_invalid_freq GW treatment of INVALID FREQuency for Hybertsen-Louie PPM
  • gw_nqlwl GW, Number of Q-points for the Long Wave-Length Limit
  • gw_qlwl GW, Q-points for the Long Wave-Length limit
  • gwgamma GW GAMMA
  • gwmem GW MEMory
  • inclvkb INCLude VKB
  • kssform Kohn Sham Structure file FORMat
  • npwkss Number of PlaneWaves in the KSS file
  • pawoptosc PAW - OPTion for the computation of the OSCillator matrix elements
  • symchi SYMmetryze \chi_0
  • zcut Z-CUT

internal:

  • %npweps Number of PlaneWaves for EPSilon (the dielectric matrix)
  • %npwwfn Number of PlaneWaves for WaveFunctioNs

Selected Input Files

libxc: