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PAW

This page gives hints on how to set parameters for a PAW calculation with the ABINIT package.

Introduction

The PAW atomic data can be used with plane waves as well as with wavelets. Specificities of PAW for use with planewaves are presented here. See topic_Wavelets for its use with wavelets.

The way the PAW method is implemented with planewaves in ABINIT is described in [Torrent2008].
The use of PAW atomic data (equivalent to pseudopotential file for the norm- conserving case) automatically launch a PAW calculation. ABINIT is provided with the JTH [Jollet2014] PAW atomic data table on the ABINIT web site.
To perform a standard PAW calculation, the input file is the same than for a norm-conserving one, except that the variable pawecutdg must be specified (see below). In the case the input variable accuracy is used, the input variable pawecutdg is automatically used.
Some physical functionalities are available only in the PAW framework: DFT+U, DMFT, local exact exchange,…

compulsory:

  • pawecutdg PAW - Energy CUToff for the Double Grid

useful:

  • ngfftdg Number of Grid points for Fast Fourier Transform: Double Grid
  • pawfatbnd PAW: print band structure in the FAT-BaND representation
  • pawovlp PAW - spheres OVerLaP allowed (in percentage)
  • pawprtden PAW: PRinT total physical electron DENsity
  • pawprtdos PAW: PRinT partial DOS contributions
  • pawprtwf PAW: PRinT WaveFunctions
  • pawspnorb PAW - option for SPiN-ORBit coupling
  • pawxcdev PAW - choice for eXchange-Correlation DEVelopment (spherical part)
  • usepawu USE PAW+U (spherical part)
  • usexcnhat USE eXchange-Correlation with NHAT (compensation charge density)

expert:

  • bxctmindg BoX CuT-off MINimum for the Double Grid (PAW)
  • mqgriddg Maximum number of Q-wavevectors for the 1-dimensional GRID for the Double Grid in PAW
  • pawcpxocc PAW - use ComPleX rhoij OCCupancies
  • pawlcutd PAW - L angular momentum used to CUT the development in moments of the Densities
  • pawlmix PAW - maximum L used in the spherical part MIXing
  • pawmixdg PAW - MIXing is done (or not) on the (fine) Double Grid
  • pawnhatxc PAW - Flag for exact computation of gradients of NHAT density in eXchange-Correlation.
  • pawnphi PAW - Number of PHI angles used to discretize the sphere around each atom.
  • pawntheta PAW - Number of THETA angles used to discretize the sphere around each atom.
  • pawnzlm PAW - only compute Non-Zero LM-moments of the contributions to the density from the spheres
  • pawoptmix PAW - OPTion for the MIXing of the spherical part
  • pawprt_b PAW PRinT band
  • pawprt_k PAW PRinT K-point
  • pawprtvol PAW: PRinT VOLume
  • pawstgylm PAW - option for the STorage of G_l(r).YLM(r)
  • pawsushat PAW - SUSceptibility, inclusion of HAT (compensation charge) contribution
  • pawusecp PAW - option for the USE of CPrj in memory (cprj=WF projected with NL projector)
  • spnorbscl SPin-ORBit SCaLing

internal:

  • %usepaw USE Projector Augmented Waves method

Selected Input Files

gpu_omp:

v4:

v5:

v8:

v9:

Tutorials

  • The tutorial on the use of PAW (PAW1) presents the Projector-Augmented Wave method, implemented in ABINIT as an alternative to norm-conserving pseudopotentials, with a sizeable accuracy and CPU time advantage.
  • The tutorial on the generation of PAW atomic data files (PAW2) presents the generation of atomic data for use with the PAW method. Prerequisite: PAW1.
  • The tutorial on the validation of a PAW atomic datafile (PAW3) demonstrates how to test a generated PAW dataset using ABINIT, against the ELK all-electron code, for diamond and magnesium. Prerequisite: PAW1 and PAW2.