Quantum ESPRESSO Properties

Property calculations for the Quantum ESPRESSO engine can be requested from two different sections: the AMS driver Properties block and the Quantum ESPRESSO engine Properties block.

The AMS Driver Properties Block

The AMS driver Properties block contains properties that are either common to other engines or have a numerical equivalent calculated using finite differences. It’s important to distinguish the Quantum ESPRESSO solution, often referred to as the “analytical” solution, from the numerical versions available at the AMS level. For properties such as NormalModes and Phonons, you can enforce the numerical calculation within AMS by specifying NormalModes%Hessian=Numerical or Phonons%Method=Numerical. If the numerical calculation is not explicitly requested, AMS will default to the analytical solution provided by the QuantumEspresso engine.

Properties
   NormalModes Yes/No
   Raman Yes/No
   Gradients Yes/No
   Phonons Yes/No
   StressTensor Yes/No
   PESPointCharacter Yes/No
End
Properties
Type:

Block

Description:

Configures which AMS level properties to calculate for SinglePoint calculations or other important geometries (e.g. at the end of an optimization).

NormalModes
Type:

Bool

Default value:

No

GUI name:

Frequencies

Description:

Calculate the frequencies and normal modes of vibration, as well as the corresponding IR intensities, if the engine supports these calculations natively or can calculate dipole moments.

Raman
Type:

Bool

Default value:

No

Description:

Requests calculation of Raman intensities for vibrational normal modes.

Gradients
Type:

Bool

Default value:

No

GUI name:

Nuclear gradients

Description:

Calculate the nuclear gradients.

Phonons
Type:

Bool

Default value:

No

Description:

Calculate the phonons (for periodic systems).

StressTensor
Type:

Bool

Default value:

No

GUI name:

Stress tensor

Description:

Calculate the stress tensor.

PESPointCharacter
Type:

Bool

Default value:

No

GUI name:

Characterize PES point

Description:

Determine whether the sampled PES point is a minimum or saddle point. Note that for large systems this does not entail the calculation of the full Hessian and can therefore be used to quickly confirm the success of a geometry optimization or transition state search.

At the AMS level, you can request the calculation of the phonons density of states (DOS) and/or the band structure:

Phonons
   BandStructure Yes/No
   DOS Yes/No
   Method [Auto | Analytical | Numerical]
End
Phonons
Type:

Block

Description:

Configures the phonons calculation.

BandStructure
Type:

Bool

Default value:

Yes

GUI name:

Calculate phonons band structure

Description:

Calculates and saves the phonon band structure for visualization. Further configuration options for analytical calculations may be available in the engine-specific settings (Phonons%BandStructure).

DOS
Type:

Bool

Default value:

Yes

GUI name:

Calculate phonon DOS

Description:

Calculates and saves the phonon density of states (DOS) for visualization. Further configuration options for analytical calculations may be available in the engine-specific settings (Phonons%DOS).

Method
Type:

Multiple Choice

Default value:

Auto

Options:

[Auto, Analytical, Numerical]

Description:

Determines how phonons are calculated. Auto selects the analytical method if supported by the engine, otherwise it defaults to numerical calculation. Configure numerical parameters in the NumericalPhonons section. Engine-specific options for analytical phonon calculations may be available in Engine%Phonons.

The QuantumEspresso Engine Properties Block

The QuantumEspresso engine Properties block contains properties specific to the engine, namely the Electronic BandStructure, DOS, and WorkFunction. These properties do not have equivalents at the AMS level.

Engine QuantumEspresso
   ...
   Properties
      BandStructure Yes/No
      DOS Yes/No
      ForceStopAfterError Yes/No
      WorkFunction Yes/No
   End
EndEngine
Properties
Type:

Block

Description:

Configures which QE level properties to calculate for SinglePoint calculations or other important geometries (e.g. at the end of an optimization).

BandStructure
Type:

Bool

Default value:

No

GUI name:

Calculate band structure

Description:

If true, the band structure is calculated and saved for visualization. To configure the parameters of the calculation, please modify the options in the the section ‘BandStructure’.

DOS
Type:

Bool

Default value:

No

GUI name:

Calculate DOS

Description:

If true, the Density-Of-States (DOS) is calculated and saved for visualization. To configure the parameters of the calculation, please modify the options in the the section ‘DOS’.

ForceStopAfterError
Type:

Bool

Default value:

No

Description:

If set to true, and a Quantum Espresso property calculation fails, the entire job will stop, preventing any subsequent property calculations from running. If set to false (default), other property calculations will proceed even if one fails.

WorkFunction
Type:

Bool

Default value:

No

GUI name:

Calculate work function

Description:

If true, the work function is calculated and saved for visualization. To configure the parameters of the calculation, please modify the options in the the section ‘WorkFunction’.

Properties Configuration Blocks

Each property described above has its own section with specific parameters, including those requested at the AMS level. The general structure is sketched below. Please note that the Phonons section is special because it contains two nested subsections: Phonons%BandStructure and Phonons%DOS. Be careful not to confuse these with their electronic section counterparts BandStructure and DOS.

Engine QuantumEspresso
   ...
   DOS
      ...
   End
   BandStructure
      ...
   End
   NormalModes
      ...
   End
   Phonons
      ...
      BandStructure
         ...
      End
      DOS
         ...
      End
   End
   WorkFunction
      ...
   End
EndEngine

Electronic Density of States (DOS, PDOS)

This section configures the parameters for calculating the electronic Density of States (DOS). These are the utilities involved:

  • pw.x (with calculation=nscf): This QE utility conducts electronic structure calculations, specifically for the non-self-consistent field (nscf) computation.

  • dos.x: A QE utility utilized for post-processing electronic structure calculations. It analyzes the electronic wavefunctions obtained from preceding calculations to determine the density of available electronic states at different energy levels.

  • projwfc.x: Another QE utility employed for post-processing electronic structure calculations. It projects the wavefunctions onto atomic orbitals or basis sets, offering insights into the composition and character of electronic states.

By default, the calculation sequence follows the order: pw.x(calculation=nscf) -> dos.x. However, enabling DOS%PDOS switches the calculation to use projwfc.x instead of dos.x.

DOS
   DeltaE float
   Emax float
   Emin float
   K_Points header # Non-standard block. See details.
      ...
   End
   K_PointsStep float
   PDOS Yes/No
   degauss float
   nbnd integer
   ngauss [SimpleGaussian | Methfessel-Paxton | ColdSmearing | Fermi-Dirac | Default]
   occupations [Smearing | Tetrahedra | Tetrahedra_lin | Tetrahedra_opt | Fixed | Auto]
End
DOS
DeltaE
Type:

Float

Default value:

0.1

Unit:

eV

GUI name:

Energy step

Description:

Energy grid step.

Emax
Type:

Float

Unit:

eV

Description:

Maximum energy for DOS plot. If unspecified, the upper band value, plus 3 times the value of the gaussian smearing if present, will be used.

Emin
Type:

Float

Unit:

eV

Description:

Minimum energy for DOS plot. If unspecified, the lower band value, minus 3 times the value of the gaussian smearing if present, will be used.

K_Points
Type:

Non-standard block

Description:

Specify the k-points to use. Choose a header appropriate for your system. Available values are: tpiba, automatic, crystal, gamma, tpiba_b, crystal_b, tpiba_c, crystal_c, and ams_kpath. See the QE documentation for details. If omitted, the k-points specified in the main QE calculation will be used. For most cases, automatic (which generates a Monkhorst-Pack grid) is recommended.

K_PointsStep
Type:

Float

Default value:

0.05

Unit:

1/Bohr

Description:

This option is used only if the header of the DOS%K_Points block is ams_kpath.

PDOS
Type:

Bool

Default value:

No

GUI name:

Calculate PDOS and Lowdin charges

Description:

If true, the partial Density-Of-States (projections on atomic basis functions) is calculated and saved for visualization. It uses the QE-utility projwfc.x. To configure the parameters of the calculation, please modify the options in the the section PROJWFC_X.

degauss
Type:

Float

Unit:

Rydberg

GUI name:

Broadening width

Description:

Gaussian broadening. See more details in sections DOS_X or PROJWFC_X.

nbnd
Type:

Integer

GUI name:

Number of bands

Description:

Number of electronic states (bands) to be calculated. Note that in spin-polarized calculations the number of k-point, not the number of bands per k-point, is doubled. Default: 20% more (minimum of 4 additional bands) than the number used in the main ‘pw.x’ calculation, regardless of the material’s insulating or metallic nature. Notice that this default is calculated differently than in standard QE.

ngauss
Type:

Multiple Choice

Default value:

Default

Options:

[SimpleGaussian, Methfessel-Paxton, ColdSmearing, Fermi-Dirac, Default]

GUI name:

Broadening type

Description:

Type of gaussian broadening: Available options are: • SimpleGaussian. • Methfessel-Paxton: Methfessel-Paxton of order 1. • ColdSmearing: Marzari-Vanderbilt-DeVita-Payne. • Fermi-Dirac: Fermi-Dirac function. • Default: See more details in sections DOS_X or PROJWFC_X.

occupations
Type:

Multiple Choice

Default value:

Auto

Options:

[Smearing, Tetrahedra, Tetrahedra_lin, Tetrahedra_opt, Fixed, Auto]

GUI name:

Non-SCF Occupations

Description:

Available options are: • Smearing: gaussian smearing for metals; see keywords smearing and degauss • Tetrahedra: Tetrahedron method, Bloechl’s version: P.E. Bloechl, PRB 49, 16223 (1994). Requires uniform grid of k-points, to be automatically generated (see block K_Points). Well suited for calculation of DOS, less so (because not variational) for force/optimization/dynamics calculations. • Tetrahedra_lin: Original linear tetrahedron method. To be used only as a reference; the optimized tetrahedron method is more efficient. • Tetrahedra_opt: optimized tetrahedron method, see M. Kawamura, PRB 89, 094515 (2014). Can be used for phonon calculations as well. • Fixed: for insulators with a gap. • Auto: Uses Tetrahedra for 3D and 2D systems, and Fixed for 0D and 1D systems.

Electronic Band Structure

This section configures the parameters for calculating the Band Structure. This involves using the following utilities:

  • kpath: This tool generates an automated high-symmetry k-path in the Brillouin zone. This is not a QE utility.

  • pw.x (with calculation=bands): This QE utility performs electronic structure calculations, particularly for bands.

  • bands.x: Another QE utility, which calculates the band structure.

The calculation sequence follows the order: kpath -> pw.x(calculation=nscf) -> bands.x.

Tip

Before calculating the band structure, make sure that the crystal unit cell corresponds to the primitive unit cell!

BandStructure
   KPathFinderConvention [Setyawan-Curtarolo | Hinuma]
   K_Points header # Non-standard block. See details.
      ...
   End
   K_PointsLabels string
   K_PointsStep float
   UseSymmetry Yes/No
   nbnd integer
End
BandStructure
KPathFinderConvention
Type:

Multiple Choice

Default value:

Setyawan-Curtarolo

Options:

[Setyawan-Curtarolo, Hinuma]

Description:

This option determines how the path through the Brillouin zone is generated when using the automatic k-point mode. Available options: • Setyawan-Curtarolo (default for 1D and 2D lattices): Uses our built-in KPath program to find a path through high-symmetry points based on the method by Setyawan and Curtarolo (https://doi.org/10.1016/j.commatsci.2010.05.010). For 2D lattices, the path is derived from the intersection of the 3D Brillouin zone with a plane. For 1D lattices, the path is simply GAMMA-Z. • Hinuma: Uses the external SeeKPath utility to generate the k-path (https://github.com/giovannipizzi/seekpath and https://doi.org/10.1016/j.commatsci.2016.10.015).

K_Points
Type:

Non-standard block

Description:

Specify the k-points to use. Choose a header appropriate for your system. Available values are: tpiba, automatic, crystal, gamma, tpiba_b, crystal_b, tpiba_c, crystal_c, and ams_kpath. See the QE documentation for details. If omitted, ams_kpath will be used for 3D systems, and gamma otherwise. For most cases, ams_kpath (which generates a convenient path along high-symmetry k-points in the Brillouin zone) is recommended.

K_PointsLabels
Type:

String

Description:

You can provide labels for your k-points, like L-GAMMA-X-U-GAMMA, separating each label with a hyphen (-) or a vertical bar (|). For example, L-GAMMA-X-U-GAMMA and L|GAMMA|X|U|GAMMA are both valid. These labels are optional and only used for display purposes when the K_Points block is specified. This option is used only if the header of the BandStructure%K_Points block is not ams_kpath. **Important:** These labels do not determine the actual k-point coordinates. You must specify the k-point coordinates separately within the K_Points section.

K_PointsStep
Type:

Float

Default value:

0.05

Unit:

1/Bohr

Description:

Step size in reciprocal space for band structure calculation. Using a smaller number will produce smoother band curves at an increased computational time. This option is used only if the header of the BandStructure%K_Points block is ams_kpath.

UseSymmetry
Type:

Bool

Default value:

Yes

Description:

If set, only the irreducible wedge of the Wigner-Seitz cell is sampled. If not, the whole (inversion-unique) Wigner-Seitz cell is sampled. Only available for Setyawan and Curtarolo convention (see KPathFinderConvention).

nbnd
Type:

Integer

GUI name:

Number of bands

Description:

Number of electronic states (bands) to be calculated. Note that in spin-polarized calculations the number of k-point, not the number of bands per k-point, is doubled. Default: 20% more (minimum of 4 additional bands) than the number used in the main ‘pw.x’ calculation, regardless of the material’s insulating or metallic nature. Notice that this default is calculated differently than in standard QE.

Analytical Normal Modes (IR & Raman Spectra)

This section configures the parameters for calculating the IR and Raman spectra. These are the utilities involved:

  • ph.x: This QE utility is used to calculate phonon frequencies and eigenvectors at a specific q-point, typically the Γ point, in the Brillouin zone. This is done using density functional perturbation theory (DFPT) to compute the dynamical matrix, which captures the interatomic force constants.

  • dynmat.x: This QE utility is used to post-process the phonon data, obtaining the IR and Raman intensities, frequencies, and vibrational modes. This step involves computing the Born effective charges and the Raman tensors, which describe the coupling of the vibrational modes to the electric field and the change in polarizability, respectively.

The calculation sequence follows the order: ph.x -> dynmat.x.

NormalModes
   ActiveAtoms integer_list
   ActiveAtomsInRegion string
   asr [no | simple | crystal | one-dim | zero-dim]
   tr2_ph float
   xq1 float
   xq2 float
   xq3 float
End
NormalModes
ActiveAtoms
Type:

Integer List

Description:

This is a list of atoms to be used in the linear response calculation. It can help estimate modes for a molecule adsorbed on a surface without requiring a full calculation. Please be aware that this is an approximation and may not be reliable. If you perform a linear response calculation for a specific atom, you should also do so for all symmetry-equivalent atoms. This option serves as an interface to the ph.x option nat_todo. This is an experimental feature!

ActiveAtomsInRegion
Type:

String

Description:

Specify the region of atoms to be included in the linear response calculation. It can help estimate modes for a molecule adsorbed on a surface without requiring a full calculation. Please be aware that this is an approximation and may not be reliable. If you perform a linear response calculation for a specific atom, you should also do so for all symmetry-equivalent atoms. This option serves as an interface to the ph.x option nat_todo. This is an experimental feature!

asr
Type:

Multiple Choice

Default value:

no

Options:

[no, simple, crystal, one-dim, zero-dim]

Description:

Indicates the type of Acoustic Sum Rule imposed. Allowed values: ‘no’, ‘simple’, ‘crystal’, ‘one-dim’, ‘zero-dim’

tr2_ph
Type:

Float

Default value:

1e-12

Description:

Threshold for self-consistency. It overwrites PH_X%tr2_ph.

xq1
Type:

Float

Default value:

0.0

Description:

First component of the phonon wavevector (q-point) at which the IR spectrum is calculated, in units of 2pi/a0 (a0 = lattice parameter). It overwrites PH_X%xq1.

xq2
Type:

Float

Default value:

0.0

Description:

Second component of the phonon wavevector (q-point) at which the IR spectrum is calculated, in units of 2pi/a0 (a0 = lattice parameter). It overwrites PH_X%xq2.

xq3
Type:

Float

Default value:

0.0

Description:

Third component of the phonon wavevector (q-point) at which the IR spectrum is calculated, in units of 2pi/a0 (a0 = lattice parameter). It overwrites PH_X%xq3.

Analytical Phonons

This section configures the parameters for calculating the phonons. These are the utilities involved:

  • kpath: This tool generates an automated high-symmetry k-path in the Brillouin zone. This is not a QE utility.

  • ph.x: This QE utility is used to calculate the phonon frequencies and eigenvectors at a uniform grid of q-points in the Brillouin zone. This is the most computationally expensive part. This step employs density functional perturbation theory (DFPT) to compute the dynamical matrix, which captures the interatomic force constants and provides the foundation for phonon analysis.

  • q2r.x: This QE utility is used to perform a Fourier transform of the interatomic force constants from the q-point grid to real space, enabling the calculation of phonon properties in a more convenient representation.

  • matdyn.x: This QE utility is employed to post-process the phonon data, allowing us to extract the phonon DOS and band structure (these are two independent calculations). This step involves calculating phonon frequencies for arbitrary q-vectors, including those along high-symmetry paths, using the interatomic force constants obtained from the dynamical matrices.

The calculation sequence follows the order: For the DOS, ph.x -> q2r.x -> matdyn.x and for the band structure, ph.x -> q2r.x -> kpath -> matdyn.x.

Phonons
   BandStructure
      KPathFinderConvention [Setyawan-Curtarolo | Hinuma]
      Q_Points header # Non-standard block. See details.
         ...
      End
      Q_PointsLabels string
      Q_PointsStep float
      UseSymmetry Yes/No
   End
   DOS
      Q_Points header # Non-standard block. See details.
         ...
      End
      degauss float
      deltaE float
      nq1 integer
      nq2 integer
      nq3 integer
   End
   K_Points header # Non-standard block. See details.
      ...
   End
   Q_Points header # Non-standard block. See details.
      ...
   End
   asr [simple | crystal | no]
   k1 integer
   k2 integer
   k3 integer
   nk1 integer
   nk2 integer
   nk3 integer
   nq1 integer
   nq2 integer
   nq3 integer
End
Phonons
BandStructure
Type:

Block

Description:

This section configures the parameters for calculating the Phonons Band Structure.

KPathFinderConvention
Type:

Multiple Choice

Default value:

Setyawan-Curtarolo

Options:

[Setyawan-Curtarolo, Hinuma]

Description:

This option determines how the path through the Brillouin zone is generated when using the automatic k-point mode. Available options: • Setyawan-Curtarolo (default for 1D and 2D lattices): Uses our built-in KPath program to find a path through high-symmetry points based on the method by Setyawan and Curtarolo (https://doi.org/10.1016/j.commatsci.2010.05.010). For 2D lattices, the path is derived from the intersection of the 3D Brillouin zone with a plane. For 1D lattices, the path is simply GAMMA-Z. • Hinuma: Uses the external SeeKPath utility to generate the k-path (https://github.com/giovannipizzi/seekpath and https://doi.org/10.1016/j.commatsci.2016.10.015).

Q_Points
Type:

Non-standard block

Description:

Specify the q-points to use. Available header values are: crystal_b, and ams_kpath. See the examples and QE documentation for details. If omitted, ams_kpath is used.

Q_PointsLabels
Type:

String

Description:

You can provide labels for your q-points, like L-GAMMA-X-U-GAMMA, separating each label with a hyphen (-) or a vertical bar (|). For example, L-GAMMA-X-U-GAMMA and L|GAMMA|X|U|GAMMA are both valid. These labels are optional and only used for display purposes when the Q_Points block is specified. This option is used only if the header of the Q_Points block is not ams_kpath. **Important:** These labels do not determine the actual k-point coordinates. You must specify the q-point coordinates separately within the Q_Points section.

Q_PointsStep
Type:

Float

Default value:

0.05

Unit:

1/Bohr

Description:

This option is used only if the header of the Phonons%BandStructure%Q_Points block is ams_kpath.

UseSymmetry
Type:

Bool

Default value:

Yes

Description:

If set, only the irreducible wedge of the Wigner-Seitz cell is sampled. If not, the whole (inversion-unique) Wigner-Seitz cell is sampled. Only available for Setyawan and Curtarolo convention (see KPathFinderConvention).

DOS
Type:

Block

Description:

Configures the parameters for calculating the Phonons DOS.

Q_Points
Type:

Non-standard block

Description:

Specify the q-points to use. Only the header automatic is allowed. This option is added for consistency, it is equivalent to set nq1, nq2, and nq3 independently.

degauss
Type:

Float

Default value:

0.0

GUI name:

Broadening width

Description:

DOS broadening in cm-1. Default: 0 - meaning use tetrahedra. It overwrites MATDYN_X%degauss.

deltaE
Type:

Float

Default value:

1.0

GUI name:

Energy step

Description:

Energy step, in cm-1, for DOS calculation: from min to max phonon energy (default: 1 cm-1). It overwrites MATDYN_X%deltaE.

nq1
Type:

Integer

Default value:

6

Description:

Uniform q-point grid for DOS calculation (includes q=0). First direction. It overwrites MATDYN_X%nk1.

nq2
Type:

Integer

Default value:

6

Description:

Uniform q-point grid for DOS calculation (includes q=0). Second direction. It overwrites MATDYN_X%nk2.

nq3
Type:

Integer

Default value:

6

Description:

Uniform q-point grid for DOS calculation (includes q=0). Third direction. It overwrites MATDYN_X%nk3.

K_Points
Type:

Non-standard block

Description:

When these block is specified the phonon program (ph.x) runs a pw non-self consistent calculation with a different k-point grid thant that used for the charge density. The only available header values are automatic or gamma. See the examples and QE documentation for details. This parameter is equivalent to nk1, nk2, nk3, k1, k2, k3 in the QE tool ph.x. If omitted, ph.x will use the same k-point grid used in the main QE calculation.

Q_Points
Type:

Non-standard block

Description:

Defines the Monkhorst-Pack grid (no offset) for sampling the Brillouin zone in the phonon calculation. The grid determines the density of q-points at which phonon frequencies will be calculated. It is used when DOS or BandStructure phonon properties are requested. The only available header values are automatic or gamma. See the examples and QE documentation for details. This parameter is equivalent to nq1, nq2, nq3 in the QE tool ph.x. If omitted, only gamma (1 1 1 0 0 0) is used.

asr
Type:

Multiple Choice

Default value:

simple

Options:

[simple, crystal, no]

GUI name:

Acoustic sum rule

Description:

Determines the acoustic sum rule (ASR) treatment. It has three options: * ‘simple’: Applies a simplified ASR where the frequencies of the three acoustic modes at q=0 are forced to be zero. * ‘crystal’: Applies the ASR considering the crystal symmetry to impose constraints on the frequencies at q=0. * ‘no’: Does not enforce any ASR. It overwrites PH_X%asr (setting it to .TRUE. if asr is not ‘no’), Q2R_X%zasr, and MATDYN_X%asr. Notice that the default value is different than in standard QE (default ‘simple’).

k1
Type:

Integer

Default value:

0

Description:

If specified, triggers a non-self-consistent calculation in ph.x with a separate Monkhorst-Pack k-point grid for phonons. This sets the k-point grid offset along the first reciprocal lattice vector for that grid.

k2
Type:

Integer

Default value:

0

Description:

If specified, triggers a non-self-consistent calculation in ph.x with a separate Monkhorst-Pack k-point grid for phonons. This sets the k-point grid offset along the second reciprocal lattice vector for that grid.

k3
Type:

Integer

Default value:

0

Description:

If specified, triggers a non-self-consistent calculation in ph.x with a separate Monkhorst-Pack k-point grid for phonons. This sets the k-point grid offset along the third reciprocal lattice vector for that grid.

nk1
Type:

Integer

Default value:

0

Description:

If specified, triggers a non-self-consistent calculation in ph.x with a separate Monkhorst-Pack k-point grid for phonons. This sets the number of k-points along the first reciprocal lattice vector for that grid.

nk2
Type:

Integer

Default value:

0

Description:

If specified, triggers a non-self-consistent calculation in ph.x with a separate Monkhorst-Pack k-point grid for phonons. This sets the number of k-points along the second reciprocal lattice vector for that grid.

nk3
Type:

Integer

Default value:

0

Description:

If specified, triggers a non-self-consistent calculation in ph.x with a separate Monkhorst-Pack k-point grid for phonons. This sets the number of k-points along the third reciprocal lattice vector for that grid.

nq1
Type:

Integer

Default value:

1

Description:

Sets the number of q-points along the first reciprocal lattice vector for the Monkhorst-Pack q-point grid for phonons. Default 1. Notice that this default is different than in standard QE (default 0).

nq2
Type:

Integer

Default value:

1

Description:

Sets the number of q-points along the second reciprocal lattice vector for the Monkhorst-Pack q-point grid for phonons. Default 1. Notice that this default is different than in standard QE (default 0).

nq3
Type:

Integer

Default value:

1

Description:

Sets the number of q-points along the third reciprocal lattice vector for the Monkhorst-Pack q-point grid for phonons. Default 1. Notice that this default is different than in standard QE (default 0).

Work Function

This section configures the parameters for calculating the Work Function. This involves using the following QE utilities:

  • pp.x: This QE utility calculates the the electrostatic potential using the results from the last calculation.

  • average.x: This QE utility performs planar and macroscopic averages of the electrostatic potential along a specified direction, which are crucial for determining the vacuum level and subsequently the work function.

The calculation sequence follows the order: pp.x -> average.x.

WorkFunction
   centralize Yes/No
   idir [x | y | z]
   npt integer
End
WorkFunction
centralize
Type:

Bool

Default value:

Yes

GUI name:

Center system

Description:

Translates the calculated electrostatic potential along the idir coordinate, respecting periodic boundary conditions, so that the geometric center of the system is at the center of the coordinate.

idir
Type:

Multiple Choice

Default value:

3

Options:

[x, y, z]

GUI name:

Use plane orthogonal to direction

Description:

1 (or x), 2 (or y) or 3 (or z). Planar average is done in the plane orthogonal to direction idir, as defined for the crystal cell. The idir parameter defaults to the value of System%edir if it’s set. Otherwise, idir is set to 3.

npt
Type:

Integer

GUI name:

Number of interpolation points

Description:

Number of points used for the final interpolation of the planar and macroscopic averages of the electrostatic potential. This controls the resolution of the averaged potential data. If npt is less than or equal to N_idir (the number of FFT grid points along the specified direction), no interpolation is performed and the raw FFT data is used. The default value is 10 * N_idir, which typically provides sufficient resolution for accurate work function calculations.