XS

Element: xs

If this element is present with valid configuration, the macroscopic dielectric function and related spectroscopic quantities in the linear regime are calculated through either time-dependent DFT (TDDFT) or the Bethe-Salpeter equation (BSE).

contains: storeexcitons (optional)
writeexcitons (optional)
excitonPlot (optional)
tddft (optional)
screening (optional)
BSE (optional)
transitions (optional)
qpointset (required)
tetra (optional)
energywindow (required)
plan (optional)
XPath: /input/xs

This element allows for specification of the following attributes: xstype (required), bfieldc, broad, dbglev, dfoffdiag, dogroundstate, emattype, emaxdf, epsdfde, fastpmat, gqmax, gqmaxtype, lmaxapw, lmaxapwwf, lmaxemat, lmaxmat, maxscl, nempty, ngridk, ngridq, nosym, pwmat, reducek, reduceq, rgkmax, scissor, skipgnd, swidth, tappinfo, tevout, vkloff

Attribute: bfieldc

This attribute overrides the homonym attribute from the groundstate/spin element.

Type: vect3d
Default: "0.0d0 0.0d0 0.0d0 "
Use: optional
XPath: /input/xs/@bfieldc


Attribute: broad

Lorentzian broadening for all spectra

Type: fortrandouble
Default: "0.01d0"
Use: optional
Unit: Hartree
XPath: /input/xs/@broad


Attribute: dbglev

Debugging level. Any value ${ > 0 }$ will produce additional debug output. The large the value, the more information is output.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/@dbglev


Attribute: dfoffdiag

"true" if also off-diagonal tensor elements for the interacting response function are to be calculated.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/@dfoffdiag


Attribute: dogroundstate

Decides if the ground state is calculated starting from scratch or using the densities from file.

Type: choose from:
fromscratch
fromfile
Default: "fromfile"
Use: optional
XPath: /input/xs/@dogroundstate


Attribute: emattype

Type of matrix element generation (band-combinations). Should only be referenced for experimental features.

Type: integer
Default: "1"
Use: optional
XPath: /input/xs/@emattype


Attribute: emaxdf

Energy cutoff for the unoccupied states in the Kohn-Sham response function and screening. This parameter ensures a cutoff at the specified energy and is defined in addition to the nempty parameter.

Type: fortrandouble
Default: "1.0d10"
Use: optional
XPath: /input/xs/@emaxdf


Attribute: epsdfde

The smallest energy difference for which the square of its inverse will be considered in the Kohn-Sham response function.

Type: fortrandouble
Default: "1.0d-8"
Use: optional
Unit: Hartree
XPath: /input/xs/@epsdfde


Attribute: fastpmat

If set to "true", a fast method to calculate APW-lo, lo-APW and lo-lo parts of the momentum matrix elements in the muffin-tin is used.

Type: boolean
Default: "true"
Use: optional
XPath: /input/xs/@fastpmat


Attribute: gqmax

${\bf |G+q|}$ cutoff for Kohn-Sham response function, screening and for expansion of Coulomb potential

Type: fortrandouble
Default: "0.0d0"
Use: optional
XPath: /input/xs/@gqmax


Attribute: gqmaxtype

Defines the way the gqmax cutoff is applied for the selection of the G-vectors. For $"|G+q|"$ G vectors are selected such that ${\bf G+q}$ lies within the gqmax cutoff. For $"|G|"$ G vectors are selected such that ${\bf G}$ lies within the gqmax cutoff.

Type: choose from:
|G+q|
|G|
Default: "|G+q|"
Use: optional
XPath: /input/xs/@gqmaxtype


Attribute: lmaxapw

Angular momentum cut-off for the APW functions.

Type: integer
Default: "10"
Use: optional
XPath: /input/xs/@lmaxapw


Attribute: lmaxapwwf

Maximum angular momentum for APW functions for q-dependent matrix elements.

Type: integer
Default: "-1"
Use: optional
XPath: /input/xs/@lmaxapwwf


Attribute: lmaxemat

Maximum angular momentum for Rayleigh expansion of ${\bf q}$-dependent plane wave factor.

Type: integer
Default: "3"
Use: optional
XPath: /input/xs/@lmaxemat


Attribute: lmaxmat

Angular momentum cut-off for the outer-most loop in the hamiltonian and overlap matrix setup.

Type: integer
Default: "5"
Use: optional
XPath: /input/xs/@lmaxmat


Attribute: maxscl

Upper limit of the self-consistency loop for the calculation of eigenvectors and eigenvalues from an existing ground-state calculation.

Type: integer
Default: "1"
Use: optional
XPath: /input/xs/@maxscl


Attribute: nempty

Number of empty states. This parameter determines the energy cutoff for the excitation spectra. For determining the number of states related to an energy cutoff, perform one iteration of a SCF calculation, setting nempty to a higher value and check the EIGVAL.OUT.

Type: integer
Default: "5"
Use: optional
XPath: /input/xs/@nempty


Attribute: ngridk

${\mathbf k}$-point grid sizes.

Type: integertriple
Default: "1 1 1"
Use: optional
XPath: /input/xs/@ngridk


Attribute: ngridq

q-point grid sizes.

Type: integertriple
Default: "1 1 1"
Use: optional
XPath: /input/xs/@ngridq


Attribute: nosym

nosym is "true" if no symmetry information should be used

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/@nosym


Attribute: pwmat

Algorithm for calculating matrix elements of plane waves. Matrix multiplications (mm) are better suited for small systems, while fast Fourier transforms (fft) are appropriate for large systems.

Type: choose from:
mm
fft
Default: "mm"
Use: optional
XPath: /input/xs/@pwmat


Attribute: reducek

reducek is "true" if ${\mathbf k}$-points are to be reduced (with crystal symmetries).

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/@reducek


Attribute: reduceq

reducek is "true" if q-points are to be reduced (with crystal symmetries).

Type: boolean
Default: "true"
Use: optional
XPath: /input/xs/@reduceq


Attribute: rgkmax

Smallest muffin-tin radius times gkmax. If set to zero (the default), this value defaults to the rgkmax set in the groundstate element.

Type: fortrandouble
Default: "0.0d0"
Use: optional
XPath: /input/xs/@rgkmax


Attribute: scissor

Scissors correction to correct the conduction band energies.

Type: fortrandouble
Default: "0.0d0"
Use: optional
Unit: Hartree
XPath: /input/xs/@scissor


Attribute: skipgnd

If set to "true", recalculation of KS eigenvalues and eigenvectors is skipped.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/@skipgnd


Attribute: swidth

Width of the smooth approximation to the Dirac delta function (must be > 0).

Type: fortrandouble
Default: "0.001d0"
Use: optional
Unit: Hartree
XPath: /input/xs/@swidth


Attribute: tappinfo

"true" to append info to output file.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/@tappinfo


Attribute: tevout

"true" if energy outputs are in eV.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/@tevout


Attribute: vkloff

The ${\mathbf k}$-point set offset. All ${\mathbf k}$-points of a regular ${\mathbf k}$-mesh (a mesh containing the Gamma point) are shifted by a constant vector given by $({\rm vkloff}_1/N_1, {\rm vkloff}_2/N_2, {\rm vkloff}_3/N_3)$, where $(N_1,N_2,N_3)$ is the division of the ${\mathbf k}$-point mesh. It should be selected such that all symmetries among the ${\mathbf k}$-points from the regular (non-shifted) mesh are broken. An exception is the case of optical spectra without local field effects where symmetries among ${\mathbf k}$-points are explicitly taken into account.

Type: vect3d
Default: "0.0d0 0.0d0 0.0d0 "
Use: optional
XPath: /input/xs/@vkloff


Attribute: xstype

Should TDDFT be used or BSE.

Type: choose from:
TDDFT
BSE
Use: required
XPath: /input/xs/@xstype

Element: storeexcitons

When present this element allows to store the exciton components (BSE eigenvectors). The number of stored excitons starting from the lowest energy one is given by the attribute MaxNumberExcitons.

Type: no content
XPath: /input/xs/storeexcitons

This element allows for specification of the following attributes: MaxNumberExcitons, MinNumberExcitons

Attribute: MaxNumberExcitons

It represents the upper limit of the number of stored excitons.

Type: integer
Default: "10"
Use: optional
XPath: /input/xs/storeexcitons/@MaxNumberExcitons


Attribute: MinNumberExcitons

It represents the lower limit of the number of stored excitons.

Type: integer
Default: "1"
Use: optional
XPath: /input/xs/storeexcitons/@MinNumberExcitons

Element: writeexcitons

When present this element allows to write the stored exciton components (BSE eigenvectors) to ASCII files. The range of excitons must lie within the stored range given by the attributes in the element storeexcitons.

Type: no content
XPath: /input/xs/writeexcitons

This element allows for specification of the following attributes: MaxNumberExcitons, MinNumberExcitons

Attribute: MaxNumberExcitons

It represents the upper limit of the number of written excitons.

Type: integer
Default: "10"
Use: optional
XPath: /input/xs/writeexcitons/@MaxNumberExcitons


Attribute: MinNumberExcitons

It represents the lower limit of the number of written excitons.

Type: integer
Default: "1"
Use: optional
XPath: /input/xs/writeexcitons/@MinNumberExcitons

Element: excitonPlot

Parameters for the electron-hole visualization.

contains: exciton (optional)
hole (required)
electron (required)
XPath: /input/xs/excitonPlot

This element allows for specification of the following attributes: epstol

Attribute: epstol

Threshold value for selecting states which contribute to the exciton.

Type: fortrandouble
Default: "1.0d-4"
Use: optional
XPath: /input/xs/excitonPlot/@epstol

Element: exciton

Electron-hole pair descriptor.

Type: no content
XPath: /input/xs/excitonPlot/exciton

This element allows for specification of the following attributes: fix, lambda

Attribute: fix

Fix position (in lattice coordinates) either of the "hole" or "electron".

Type: string
Default: "hole"
Use: optional
XPath: /input/xs/excitonPlot/exciton/@fix


Attribute: lambda

The index of the stored exciton.

Type: integer
Default: "1"
Use: optional
XPath: /input/xs/excitonPlot/exciton/@lambda

Element: hole

For the exciton wavefunction visualization: Real space grid for the hole distribution.

contains: plot1d (optional)
plot2d (optional)
plot3d (optional)
XPath: /input/xs/excitonPlot/hole

Element: electron

For the exciton wavefunction visualization: Real space grid for the electron distribution.

contains: plot1d (optional)
plot2d (optional)
plot3d (optional)
XPath: /input/xs/excitonPlot/electron

Element: tddft

Type: no content
XPath: /input/xs/tddft

This element allows for specification of the following attributes: acont, ahc, alphalrc, alphalrcdyn, aresdf, aresfxc, betalrcdyn, do, drude, fxcbsesplit, fxctype, intraband, kerndiag, lindhard, lmaxalda, mdfqtype, nwacont, torddf, tordfxc

Attribute: acont

Set to "true" if analytic continuation from the imaginary axis to the real axis is to be performed.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@acont


Attribute: ahc

By setting it to "true", the anomalous Hall conductivity (AHC) term is included in the calculation of the dielectric tensor [see PRB 86, 125139 (2012)]. In this case, the MOKE.OUT output file is generated, containing the MOKE spectrum. This attribute only has effect when local field effects are neglected (gqmax=0) and q=0.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@ahc


Attribute: alphalrc

$\alpha$-parameter for the static long range contribution (LRC) model xc kernel.

Type: fortrandouble
Default: "0.0d0"
Use: optional
XPath: /input/xs/tddft/@alphalrc


Attribute: alphalrcdyn

$\alpha$-parameter for the dynamical long range contribution (LRC) model xc kernel.

Type: fortrandouble
Default: "0.0d0"
Use: optional
XPath: /input/xs/tddft/@alphalrcdyn


Attribute: aresdf

Set to "true" if to consider the anti-resonant part for the dielectric function.

Type: boolean
Default: "true"
Use: optional
XPath: /input/xs/tddft/@aresdf


Attribute: aresfxc

Set to "true" if to consider the anti-resonant part for the MBPT derived xc-kernels.

Type: boolean
Default: "true"
Use: optional
XPath: /input/xs/tddft/@aresfxc


Attribute: betalrcdyn

$\beta$-parameter for the dynamical long range contribution (LRC) model xc kernel.

Type: fortrandouble
Use: optional
XPath: /input/xs/tddft/@betalrcdyn


Attribute: do

Decides if the TDDFT calculation is to be resumed starting from a new xc kernel or is to be skipped.

Type: choose from:
fromscratch
fromkernel
Default: "fromscratch"
Use: optional
XPath: /input/xs/tddft/@do


Attribute: drude

Parameters defining semiclassical Drude approximation to intraband term. The first value determines the plasma frequency $\omega_p$ and the second the inverse relaxation time $\omega_{\tau}$:$\chi_0^D=\frac{1}{\omega}\frac{\omega_p^2}{\omega+i\omega_{\tau}}$

Type: vect2d
Default: "0.0d0 0.0d0"
Use: optional
XPath: /input/xs/tddft/@drude


Attribute: fxcbsesplit

Split parameter for degeneracy in energy differences of MBPT derived xc kernels. See A. Marini, Phys. Rev. Lett., 91, (2003) 256402.

Type: fortrandouble
Default: "1.0d-5"
Use: optional
Unit: Hartree
XPath: /input/xs/tddft/@fxcbsesplit


Attribute: fxctype

Defines which xc kernel is to be used. Examples on the use of the different kernels can be found online on the Tutorial "TDDFT Calculations with Different Kernels" on www.exciting-code.org. In the options indicated below, if the suffix "_NLF" is present, then local-field effects are neglected (scalar kernel). Otherwise the kernel is a matrix of the size of the number of $\mathbf{G}$-vectors, whose diagonal elements are all equal. The available kernels $f_{xc}$ are:

  • "RPA" - Random-phase approximation kernel. $f_{xc}=0$
  • "LRCstatic[_NLF]" - Long-range correction kernel.
(1)
\begin{align} f_{xc}=-\frac{\alpha}{\mathbf{q}^2}. \end{align}

See S. Botti et al., Phys. Rev. B 69, 155112 (2004)

  • "LRCdyn[_NLF]" - Dynamical long-range correction kernel.
(2)
\begin{align} f_{xc}=-\frac{\alpha+\beta \omega^2}{\mathbf{q}^2} \end{align}

with $\alpha$ given by the value of alphalrcdyn and $\beta$ given by the value of betalrcdyn. See S. Botti et al., Phys. Rev. B 72, 125203 (2005)

  • "ALDA" - Adiabatic LDA kernel.
(3)
\begin{align} f_{xc}(\mathbf{r},\mathbf{r}',t-t')=\frac{\delta V_{xc}(\mathbf{r})}{\delta n(\mathbf{r}')}\delta(t-t'). \end{align}

In this implementation, $V_{xc}(\mathbf{r})$ is the spin-unpolarised exchange-correlation potential corresponding to the Perdew-Wang parameterisation of Ceperley-Alder's Monte-Carlo data (see Phys. Rev. B 45, 13244 (1992) and Phys. Rev. Lett. 45, 566 (1980)).

  • "MB1[_NLF]" - BSE derived xc kernel. See L. Reining et al., Phys. Rev. Lett. 88, 066404 (2002) and A. Marini et al., Phys. Rev. Lett. 91, 256402 (2003).
  • "BO" - Bootstrap kernel.
(4)
\begin{align} f_{xc}=\frac{\varepsilon^{-1}(\omega=0)}{\chi_{00}(\omega=0)}. \end{align}

See S. Sharma et al., Phys. Rev. Lett. 107, 186401 (2011).

  • "BO_SCALAR" - Scalar version of the bootstrap kernel. $f_{xc}=\left[\varepsilon_M(\omega=0)\chi_{00}(\omega=0)\right]^{-1}$. See S. Sharma et al., Phys. Rev. Lett. 107, 186401 (2011).
  • "RBO" - RPA bootstrap kernel. $f_{xc}=\left[\varepsilon^{RPA}_M(\omega=0)\overline{\chi}_{00}^{RPA}(\omega=0)\right]^{-1}$. See S. Rigamonti et al., Phys. Rev. Lett. 114, 146402 (2015).
Type: choose from:
RPA
LRCstatic_NLF
LRCstatic
LRCdyn_NLF
LRCdyn
ALDA
MB1_NLF
MB1
BO
BO_SCALAR
RBO
Default: "RPA"
Use: optional
XPath: /input/xs/tddft/@fxctype


Attribute: intraband

By setting it to "true", the intraband contribution is included in the calculation for the finite q.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@intraband


Attribute: kerndiag

Set to "true" if only diagonal part of xc-kernel is to be used.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@kerndiag


Attribute: lindhard

Set to "true" if Lindhard-like function is to be calculated.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@lindhard


Attribute: lmaxalda

Angular momentum cutoff for Rayleigh expansion of exponential factor for ALDA-kernel.

Type: integer
Default: "3"
Use: optional
XPath: /input/xs/tddft/@lmaxalda


Attribute: mdfqtype

Treatment of macroscopic dielectric function for ${\bf Q}$-point outside of Brillouin zone. A value of 0 uses the full ${\bf Q}$ and the $({\bf 0},{\bf 0})$ component of the microscopic dielectric matrix is used. A value of 1 invokes a decomposition ${\bf Q}={\bf q}+{\bf G}_{\bf q}$ and the $({\bf Q}_{\bf q},{\bf Q}_{\bf q})$ component of the microscopic dielectric matrix is used.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/tddft/@mdfqtype


Attribute: nwacont

Number of energy intervals (on imaginary axis) for analytic continuation.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/tddft/@nwacont


Attribute: torddf

Set to "true" if to consider the time-ordered version of the dielectric function.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@torddf


Attribute: tordfxc

Set to "true" if to consider the time-ordered version of xc kernel (MBPT derived kernels only).

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tddft/@tordfxc

Element: screening

Type: no content
XPath: /input/xs/screening

This element allows for specification of the following attributes: do, nempty, ngridk, nosym, reducek, rgkmax, screentype, vkloff

Attribute: do

Decides if the calculation of the screening is done from scratch or is to be skipped.

Type: choose from:
fromscratch
skip
Default: "fromscratch"
Use: optional
XPath: /input/xs/screening/@do


Attribute: nempty

Number of empty states.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/screening/@nempty


Attribute: ngridk

${\mathbf k}$-point grid sizes for screening.

Type: integertriple
Default: "0 0 0"
Use: optional
XPath: /input/xs/screening/@ngridk


Attribute: nosym

nosym is "true" if no symmetry information should be used for screening.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/screening/@nosym


Attribute: reducek

reducek is "true" if ${\mathbf k}$-points are to be reduced with crystal symmetries for screening.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/screening/@reducek


Attribute: rgkmax

The smallest muffin-tin radius times gkmax for screening.

Type: fortrandouble
Default: "0.0d0"
Use: optional
XPath: /input/xs/screening/@rgkmax


Attribute: screentype

Defines which type of screening is to be used.

Type: choose from:
full
diag
noinvdiag
longrange
Default: "full"
Use: optional
XPath: /input/xs/screening/@screentype


Attribute: vkloff

${\mathbf k}$-point offset for screening.

Type: vect3d
Default: "-1.0d0 -1.0d0 -1.0d0"
Use: optional
XPath: /input/xs/screening/@vkloff

Element: BSE

Type: no content
XPath: /input/xs/BSE

This element allows for specification of the following attributes: aresbse, bsedirsing, bsetype, fbzq, lmaxdielt, nexcitmax, ngridksub, nleblaik, nosym, nstlbse, nstlxas, reducek, rgkmax, sciavbd, sciavqbd, sciavqhd, sciavqwg, sciavtype, scrherm, vkloff, xas, xasatom, xasedge, xasspecies

Attribute: aresbse

Is set to "true" if to consider the anti-resonant part for the BSE spectrum.

Type: boolean
Default: "true"
Use: optional
XPath: /input/xs/BSE/@aresbse


Attribute: bsedirsing

"true" if effective singular part of direct term of BSE Hamiltonian is to be used.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@bsedirsing


Attribute: bsetype

Defines which parts of the BSE Hamiltonian are to be considered.

Type: choose from:
IP
RPA
singlet
triplet
Default: "singlet"
Use: optional
XPath: /input/xs/BSE/@bsetype


Attribute: fbzq

Set to "true" if q-point set is to be taken from the first Brillouin zone.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@fbzq


Attribute: lmaxdielt

Angular momentum cutoff of the spherical harmonics expansion of the dielectric matrix.

Type: integer
Default: "14"
Use: optional
XPath: /input/xs/BSE/@lmaxdielt


Attribute: nexcitmax

Maximum number of excitons to be considered in a BSE calculation.

Type: integer
Default: "100"
Use: optional
XPath: /input/xs/BSE/@nexcitmax


Attribute: ngridksub

The sub-grid of a BSE double grid run. Any value larger than 1 triggers a computation following this scheme: the BSE is solved several times on coarse grids, as given by ngridk and ngridq, which are shifted to all symmetry non-equivalent points of the sub-grid. The latter are distributed uniformly between the k-points of the coarse grid. The final results are obtained by averaging all the spectra yielded in this way, what is expected to be almost as good as solving the BSE on the fine grid, at much less computational cost.

Type: integertriple
Default: "1 1 1"
Use: optional
XPath: /input/xs/BSE/@ngridksub


Attribute: nleblaik

Number of points used for the Lebedev-Laikov grids must be selected according to V.I. Lebedev, and D.N. Laikov, Doklady Mathematics, 59 (1999) 477.

Type: integer
Default: "5810"
Use: optional
XPath: /input/xs/BSE/@nleblaik


Attribute: nosym

Set to "true" if no symmetry information should be used for BSE.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@nosym


Attribute: nstlbse

Range of bands included for the BSE calculation. The first pair of numbers corresponds to the band index for local orbitals and valence states (counted from the lowest eigenenergy), the second pair corresponds to the band index of the conduction states (counted from the Fermi level).

Type: integerquadrupel
Default: "0 0 0 0"
Use: optional
XPath: /input/xs/BSE/@nstlbse


Attribute: nstlxas

Range of bands included for the BSE calculation. The pair corresponds to the band index of the conduction states (counted from the Fermi level).

Type: integerpair
Default: "0 0"
Use: optional
XPath: /input/xs/BSE/@nstlxas


Attribute: reducek

reducek is "true" if ${\mathbf k}$-points are to be reduced with crystal symmetries for BSE.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@reducek


Attribute: rgkmax

Smallest muffin-tin radius times gkmax.

Type: fortrandouble
Default: "0.0d0"
Use: optional
XPath: /input/xs/BSE/@rgkmax


Attribute: sciavbd

"true" if the body of the screened Coulomb interaction is to be averaged (q=0).

Type: boolean
Default: "true"
Use: optional
XPath: /input/xs/BSE/@sciavbd


Attribute: sciavqbd

"true" if the body of the screened Coulomb interaction is to be averaged (q!=0).

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@sciavqbd


Attribute: sciavqhd

"true" if the head of the screened Coulomb interaction is to be averaged (q!=0).

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@sciavqhd


Attribute: sciavqwg

"true" if the wings of the screened Coulomb interaction are to be averaged (q!=0).

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@sciavqwg


Attribute: sciavtype

Defines how the screened Coulomb interaction matrix is to be averaged (important for the singular terms).

Type: choose from:
spherical
screendiag
invscreendiag
Default: "spherical"
Use: optional
XPath: /input/xs/BSE/@sciavtype


Attribute: scrherm

Method of how an almost Hermitian matrix is inverted. A value of 0: invert full matrix (matrix is allowed to be not strictly Hermitian); a value of 1: take the Hermitian average for inversion; a value of 2: assume Hermitian and use the upper triangle; a value of 3: assume Hermitian and use the lower triangle.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/BSE/@scrherm


Attribute: vkloff

${\mathbf k}$-point offset for BSE.

Type: vect3d
Default: "-1.0d0 -1.0d0 -1.0d0"
Use: optional
XPath: /input/xs/BSE/@vkloff


Attribute: xas

Set to "true" to perform BSE X-rasy absorption spectroscopy (XAS) calculation

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/BSE/@xas


Attribute: xasatom

Atom number for which the XAS is calculated.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/BSE/@xasatom


Attribute: xasedge

Defines the initial states of the XAS calculation.

Type: choose from:
K
L1
L2
L3
L23
M1
M2
M3
M23
M4
M5
M45
Default: "K"
Use: optional
XPath: /input/xs/BSE/@xasedge


Attribute: xasspecies

Species number for which the XAS is calculated.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/BSE/@xasspecies

Element: transitions

Describe transitions between Kohn-Sham states for the calculation of the Kohn-Sham response function (and screening) here. Individual transitions as well as a range (or a list) of initial and final states can be defined.

contains: individual (optional)
ranges (optional)
lists (optional)
XPath: /input/xs/transitions

Element: individual

A list of individual transitions consisting of an initial state a final state and a ${\mathbf k}$-point is given here. If the list is empty, no transitions are considered.

contains: trans (optional)
XPath: /input/xs/transitions/individual

Element: trans

An individual transition consisting of an initial state a final state and a ${\mathbf k}$-point is given here. Values of zero correspond to the inclusion of all initial and final states and all ${\mathbf k}$-points and can be used as "wildcards" (default). Therefore, an empty element amounts to include all transitions.

Type: no content
XPath: /input/xs/transitions/individual/trans

This element allows for specification of the following attributes: action, final, initial, kpointnumber

Attribute: action

Select to include or exclude states. If a state is included as well as excluded several times the last definition (in the sequence of individual transitions) counts.

Type: choose from:
include
exclude
Default: "include"
Use: optional
XPath: /input/xs/transitions/individual/trans/@action


Attribute: final

Final state of individual transition. A value of zero (default) means to include all states.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/individual/trans/@final


Attribute: initial

Initial state of individual transition. A value of zero (default) means to include all states.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/individual/trans/@initial


Attribute: kpointnumber

Number of ${\mathbf k}$-points to be considered. A value of zero (default) means to include all ${\mathbf k}$-points.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/individual/trans/@kpointnumber

Element: ranges

A list of ranges of transitions (initial state as well as final state ranges) and a ${\mathbf k}$-point are given here. An empty list amounts to no transitions at all.

contains: range (optional)
XPath: /input/xs/transitions/ranges

Element: range

A range of transitions (for initial as well as final states) is given here. A range consists of a "start" and a "stop" values as well as a ${\mathbf k}$-point. Values of zero correspond to starting at the first state and stopping at the last state and considering all ${\mathbf k}$-points. They can be used as "wildcards" (default). Therefore, an empty element corresponds to the full initial/final state range for all ${\mathbf k}$-points.

Type: no content
XPath: /input/xs/transitions/ranges/range

This element allows for specification of the following attributes: statestype (required), action, kpointnumber, start, stop

Attribute: action

Select to include or exclude states. If a state is included as well as excluded several times the last definition (in the sequence of individual transitions) counts.

Type: choose from:
include
exclude
Default: "include"
Use: optional
XPath: /input/xs/transitions/ranges/range/@action


Attribute: kpointnumber

Number of ${\mathbf k}$-point to be considered. A value of zero (default) means to include all ${\mathbf k}$-point.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/ranges/range/@kpointnumber


Attribute: start

Start value (first state) for range. A value of zero (default) means to start from the first state.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/ranges/range/@start


Attribute: statestype

Select for initial or final state range.

Type: choose from:
initialstates
finalstates
Use: required
XPath: /input/xs/transitions/ranges/range/@statestype


Attribute: stop

Stop value (last state) for range. A value of zero (default) means to stop at the last state (no upper limit).

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/ranges/range/@stop

Element: lists

A list of initial and final state entries to be considered for transitions. An empty list amounts to no transitions at all.

contains: istate (optional)
XPath: /input/xs/transitions/lists

Element: istate

An initial or final state and corresponding ${\mathbf k}$-point is given here. Values of zero correspond to considering all initial/final states for all ${\mathbf k}$-points. They can be used as "wildcards" (default). Therefore, an empty element corresponds to the full initial/final state set for all ${\mathbf k}$-points.

Type: no content
XPath: /input/xs/transitions/lists/istate

This element allows for specification of the following attributes: statestype (required), action, kpointnumber, state

Attribute: action

Select to include or exclude states. If a state is included as well as excluded several times the last definition (in the sequence of individual transitions) counts.

Type: choose from:
include
exclude
Default: "include"
Use: optional
XPath: /input/xs/transitions/lists/istate/@action


Attribute: kpointnumber

Number of ${\mathbf k}$-point to be consider. A value of zero (default) means to include all ${\mathbf k}$-point.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/lists/istate/@kpointnumber


Attribute: state

The state to be considered. A value of zero (default) means to include all states.

Type: integer
Default: "0"
Use: optional
XPath: /input/xs/transitions/lists/istate/@state


Attribute: statestype

Select for initial or final state list.

Type: choose from:
initialstates
finalstates
Use: required
XPath: /input/xs/transitions/lists/istate/@statestype

Element: tetra

Type: no content
XPath: /input/xs/tetra

This element allows for specification of the following attributes: cw1k, kordexc, qweights, tetradf, tetraocc

Attribute: cw1k

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tetra/@cw1k


Attribute: kordexc

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tetra/@kordexc


Attribute: qweights

Choice of weights and nodes for the tetrahedron method and non-zero Q-point.

Type: integer
Default: "1"
Use: optional
XPath: /input/xs/tetra/@qweights


Attribute: tetradf

"true" if tetrahedron method is used for the ${\mathbf k}$-space integration in the Kohn-Sham response function.

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tetra/@tetradf


Attribute: tetraocc

Type: boolean
Default: "false"
Use: optional
XPath: /input/xs/tetra/@tetraocc

Element: plan

contains: doonly (optional)
XPath: /input/xs/plan

Element: doonly

Type: no content
XPath: /input/xs/plan/doonly

This element allows for specification of the following attributes: task (required)

Attribute: task

Type: choose from:
xsgeneigvec
tetcalccw
writepmatxs
writeemat
df
df2
idf
scrgeneigvec
scrtetcalccw
scrwritepmat
screen
scrcoulint
exccoulint
bse
bsegenspec
writebevec
kernxc_bse
writebandgapgrid
writepmat
dielectric
writepmatasc
pmatxs2orig
writeematasc
writepwmat
emattest
x0toasc
x0tobin
fxc_alda_check
kernxc_bse3
testxs
xsestimate
xstiming
testmain
excitonWavefunction
portstate(1)
portstate(2)
portstate(-1)
portstate(-2)
Use: required
XPath: /input/xs/plan/doonly/@task

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.

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