Eph

Element: eph

Electron-phonon calculation setup.

contains:	ephmat (optional) el_interpolation (optional) ph_interpolation (optional) eph_interpolation (optional) el_self_energy (optional) target (optional)
XPath:	/input/eph

This element allows for specification of the following attributes: efermi, elphbolt, scissor, scissor_direction, wfrange

Attribute: efermi

Fermi energy. Can be manually set to, e.g. VBM or CBm. Default: Automatic determination.

Type:	fortrandouble
Default:	"0.0"
Use:	optional
Unit:	Hartree
XPath:	/input/eph/@efermi

Attribute: elphbolt

Run compatible with `elphbolt` code, i.e., use elphbolt compatible non-analytic dynamical matrix.

Type:	boolean
Default:	"false"
Use:	optional
XPath:	/input/eph/@elphbolt

Attribute: scissor

Scissor operator to apply. See also scissor_direction.

Type:	fortrandouble
Default:	"0.0"
Use:	optional
Unit:	Hartree
XPath:	/input/eph/@scissor

Attribute: scissor_direction

Specify to apply scissor shift to occupied, unoccupied states or symmetrically to both.

Type:	choose from: occupied unoccupied symmetric
Default:	"symmetric"
Use:	optional
XPath:	/input/eph/@scissor_direction

Attribute: wfrange

Lower and upper bound of Wannier functions to be included in EPH calculation. Default is all.

Type:	integerpair
Default:	"1 0"
Use:	optional
XPath:	/input/eph/@wfrange

Element: ephmat

Settings for calculation of electron-phonon matrix elements.

Type:	no content
XPath:	/input/eph/ephmat

This element allows for specification of the following attributes: do, standard

Attribute: do

Decides if the matrix elements are (re)computed from scratch or if the calculation is skipped.

Type:	choose from: fromscratch skip
Default:	"fromscratch"
Use:	optional
XPath:	/input/eph/ephmat/@do

Attribute: standard

Compute standard electron-phonon matrix elements.

Type:	boolean
Default:	"true"
Use:	optional
XPath:	/input/eph/ephmat/@standard

Element: el_interpolation

Interpolate electron energies on target set and write result to file.

Type:	no content
XPath:	/input/eph/el_interpolation

This element allows for specification of the following attributes: format

Attribute: format

Output format. Choose from plain text or json.

Type:	choose from: text json
Default:	"text"
Use:	optional
XPath:	/input/eph/el_interpolation/@format

Element: ph_interpolation

Interpolate phonon frequencies on target set and write result to file.

Type:	no content
XPath:	/input/eph/ph_interpolation

This element allows for specification of the following attributes: format

Attribute: format

Output format. Choose from plain text or json.

Type:	choose from: text json
Default:	"text"
Use:	optional
XPath:	/input/eph/ph_interpolation/@format

Element: eph_interpolation

Interpolate electron-phonon matrix elements on target set and write result to file.

Type:	no content
XPath:	/input/eph/eph_interpolation

This element allows for specification of the following attributes: epsdegel, epsdegph, fix, format, include_polar, vplfix

Attribute: epsdegel

Maximum difference between electron energies to be considered degenerate.

Type:	fortrandouble
Default:	"1d-4"
Use:	optional
Unit:	Hartree
XPath:	/input/eph/eph_interpolation/@epsdegel

Attribute: epsdegph

Maximum difference between phonon energies to be considered degenerate.

Type:	fortrandouble
Default:	"1d-5"
Use:	optional
Unit:	Hartree
XPath:	/input/eph/eph_interpolation/@epsdegph

Attribute: fix

Choose whether to fix electron momentum ${\mathbf k}$ or phonon momentum ${\mathbf q}$. The other will be taken from the target set.

Type:	choose from: k q
Default:	"k"
Use:	optional
XPath:	/input/eph/eph_interpolation/@fix

Attribute: format

Output format. Choose from plain text or json.

Type:	choose from: text json
Default:	"text"
Use:	optional
XPath:	/input/eph/eph_interpolation/@format

Attribute: include_polar

Include long-range polar Fröhlich coupling in polar materials.

Type:	boolean
Default:	"true"
Use:	optional
XPath:	/input/eph/eph_interpolation/@include_polar

Attribute: vplfix

Fixed momentum vector in lattice coordinates.

Type:	vect3d
Default:	"0.0d0 0.0d0 0.0d0"
Use:	optional
XPath:	/input/eph/eph_interpolation/@vplfix

Element: el_self_energy

Settings for calculation of electron self-energy.

contains:	freq_grid (optional) output_settings (optional)
XPath:	/input/eph/el_self_energy

This element allows for specification of the following attributes: do, integration, ngridbz, swidth, tempset, vbzoff

Attribute: do

Decides if the self energy is (re)computed from scratch, read from file or if the calculation is skipped.

Type:	choose from: fromscratch fromfile skip
Default:	"fromscratch"
Use:	optional
XPath:	/input/eph/el_self_energy/@do

Attribute: integration

Integration method for BZ integral. kramers-kronig: Use tetrahedron integration for the imaginary part of the self-energy and obtain real part from Kramers-Kronig relation. smearing: Use imaginary smearing (eta) (see swidth).

Type:	choose from: smearing kramers-kronig
Default:	"kramers-kronig"
Use:	optional
XPath:	/input/eph/el_self_energy/@integration

Attribute: ngridbz

${\mathbf q}$-point grid used for Brillouin zone integration.

Type:	integertriple
Default:	"2 2 2"
Use:	optional
XPath:	/input/eph/el_self_energy/@ngridbz

Attribute: swidth

Smearing width (eta). For tetrahedron integration an artificial Lorentzian broadening with this width is applied.

Type:	fortrandouble
Default:	"0.001"
Use:	optional
Unit:	Hartree
XPath:	/input/eph/el_self_energy/@swidth

Attribute: tempset

Temperature set for which to calculate self-energy. Given as lower bound, upper bound, step.

Type:	vect3d
Default:	"0.0d0 0.0d0 0.0d0"
Use:	optional
Unit:	Kelvin
XPath:	/input/eph/el_self_energy/@tempset

Attribute: vbzoff

The ${\mathbf q}$-point offset vector for integration grid in lattice coordinates. It is recommended to shift the grid in polar materials to avoid Gamma point sampling.

Type:	vect3d
Default:	"0.0d0 0.0d0 0.0d0"
Use:	optional
XPath:	/input/eph/el_self_energy/@vbzoff

Element: output_settings

Settings for human-readable output of electron self-energy and spectral function.

contains:	freq_grid (optional)
XPath:	/input/eph/el_self_energy/output_settings

This element allows for specification of the following attributes: directory, interpolation_method

Attribute: directory

Name of directory to save human-readable output in.

Type:	string
Default:	"."
Use:	optional
XPath:	/input/eph/el_self_energy/output_settings/@directory

Attribute: interpolation_method

Method used for interpolating self-energy on output grid.

Type:	choose from: spline linear
Default:	"spline"
Use:	optional
XPath:	/input/eph/el_self_energy/output_settings/@interpolation_method

Element: target

Set of reciprocal space points ${\mathbf p}$ for target quantities. The meaning (electron or phonon wavevector) varies depending on the context. Can be a regular grid or a 1D path.

contains:	plot1d (optional)
XPath:	/input/eph/target

This element allows for specification of the following attributes: ngridp, reducep, vploff

Attribute: ngridp

Regular ${\mathbf p}$-point grid size. If a target path is specified, this is ignored.

Type:	integertriple
Default:	"0 0 0"
Use:	optional
XPath:	/input/eph/target/@ngridp

Attribute: reducep

Flag to specify whether the ${\mathbf p}$-point grid is reduced using symmetry operations.

Type:	boolean
Default:	"true"
Use:	optional
XPath:	/input/eph/target/@reducep

Attribute: vploff

Offset of the ${\mathbf p}$-point grid.

Type:	vect3d
Default:	"0.0d0 0.0d0 0.0d0"
Use:	optional
XPath:	/input/eph/target/@vploff

Reused Elements

The following elements can occur more than once in the input file. There for they are listed separately.

Data Types

The Input definition uses derived data types. These are described here.