The xml element input is the root element of the exciting input file. It must contain one element structure and the element groundstate .

Find a minimal input file instance described here.

List of attributes: xsltpath , scratchpath

Attribute: scratchpath

This is the path to scratch space where the eigenvector files EVECFV.OUT, EVECSV.OUT and OCCSV.OUT will be written. If the local directory is accessed via a network then scrpath can be set to a directory on a local disk

Attribute: xsltpath

Title of the input file.

List of attributes: target

Attribute: target

Output format for conversion. Either the binary file STATE.OUT is converted to the XML file STATE.xml or vice versa.

List of attributes: source

Attribute: source

Extract information from STATE.OUT or STATE.xml file. A skeleton input is created and written to STATE_input.xml .

The structure element contains all structural information such as unit cell and atom positions.

List of attributes: speciespath , molecule , vacuum , epslat , autormt , primcell , tshift

Attribute: autormt

If "true" automatic determination of the muffin tin radii is allowed.

Attribute: epslat

Vectors with lengths less than this are considered zero.

Attribute: molecule

Has to be set to "true" if one wants to calculate an isolated molecule. If it is "true" , then the atomic positions,${\bf a}$, are assumed to be in Cartesian coordinates. The lattice vectors are also set up automatically with the i-th lattice vector given by

where

with$\alpha$and$\beta$labeling atoms, and$d_{\rm vac}$determines the size of the vacuum around the molecule. The last variable is set by the attribute vacuum .

Attribute: primcell

Allows the primitive unit cell to be determined automatically from the conventional cell. This is done by searching for lattice vectors among all those which connect atomic sites, and using the three shortest ones which produce a unit cell with non-zero volume.

Attribute: speciespath

Gives the path to the directory containing the species files. It can be an HTTP URL too (needs wget ).

Attribute: tshift

Set to it to "true" if the crystal can be shifted such that the atom closest to the origin is exactly at the origin.

Attribute: vacuum

Determines the size of the vacuum around the molecule.

The crystal element defines the unit cell of the calculation.

List of attributes: scale , stretch

Attribute: scale

The attribute scale scales all the lattice vectors. This is useful for varying the volume.

Attribute: stretch

Allows for a separate scaling of each lattice vector. "1 1 1" means no scaling.

The basevect element defines one basis vector.

The species element defines the atom species. It contains a atom element for each atom of the species.

List of attributes: speciesfile , chemicalSymbol , atomicNumber , rmt , href

Attribute: atomicNumber

Is an optional attribute can be given to simplify visualization and converters. It is not used by exciting

Attribute: chemicalSymbol

Can be given to simplify visualization and converters. It is ignored by exciting

Attribute: href

Attribute: rmt

Muffin tin radius this optional parameter allows to override species file or automatic determination

Attribute: speciesfile

Defines the file from which the species definition is read. It is looked up in the species directory specified by the species path.

The atom element carries all the attributes of a single atom in the unit cell. The position is given by the coord attribute

List of attributes: coord , bfcmt , mommtfix

Attribute: bfcmt

Muffin-tin external magnetic field in Cartesian coordinates for atom.

Attribute: coord

Position in lattice coordinates.

Attribute: mommtfix

If present defines LDA plus U parameters for species

List of attributes: l , U , J

Attribute: J

Attribute: U

Attribute: l

The groundstate element is required for any calculation. Its attributes are the parameters and methods used to calculate the groundstate density.

List of attributes: do , ngridk , rgkmax , epspot , epsengy , epsforce , rmtapm , swidth , stype , findlinentype , isgkmax , gmaxvr , nempty , nosym , frozencore , autokpt , radkpt , reducek , tfibs , tforce , lmaxapw , maxscl , chgexs , deband , epsband , dlinenfermi , epschg , epsocc , mixer , beta0 , betainc , betadec , lradstep , nprad , xctype , ldapu , lmaxvr , fracinr , lmaxinr , lmaxmat , vkloff , npsden , cfdamp , nosource , tevecsv , nwrite , ptnucl

Attribute: autokpt

Decides if the-point set is to be determined automatically

Attribute: beta0

Initial value for mixing parameter. Used in linear mixing.

Attribute: betadec

Mixing parameter decrease. Used in linear mixing.

Attribute: betainc

Mixing parameter increase. Used in linear mixing.

Attribute: cfdamp

Damping coefficient for characteristic function.

Attribute: chgexs

This controls the amount of charge in the unit cell beyond that required to maintain neu-trality. It can be set positive or negative depending on whether electron or hole doping is required.

Attribute: deband

Initial band energy step size The initial step length used when searching for the band energy, which is used as the APW linearization energy. This is done by first searching upwards in energy until the radial wavefunction at the muffin-tin radius is zero. This is the energy at the top of the band, denoted$E_{\rm t}$. A downward search is now performed from$E_{\rm t}$until the slope of the radial wavefunction at the muffin-tin radius is zero. This energy,$E_{\rm b}$, is at the bottom of the band. The band energy is taken as$(E_{\rm t}+E_{\rm b})/2$. If either$E_{\rm t}$or$E_{\rm b}$cannot be found then the band energy is set to the default value.

Attribute: dlinenfermi

Energy difference between linearisation and Fermi energy.

Attribute: do

Decides if the groundstate run is skipped, calculated from scratch, or continued from the file STATE.OUT.

Attribute: epsband

Energy tolerance for search of linearization energies.

Attribute: epschg

Maximum allowed error in the calculated total charge beyond which a warning message will be issued.

Attribute: epsengy

Energy convergence tolerance.

Attribute: epsforce

Convergence tolerance for the forces during the SCF run.

Attribute: epsocc

smallest occupancy for which a state will contribute to the density.

Attribute: epspot

If the RMS change in the effective potential and magnetic field is smaller than epspot , then the self-consistent loop is considered converged and exited. For structural optimization runs this results in the forces being calculated, the atomic positions updated and the loop restarted. See also maxscl.

Attribute: findlinentype

Select method to determine the linearization energies.

Attribute: fracinr

Fraction of the muffin-tin radius up to which lmaxinr is used as the angular momentum cut-off.

Attribute: frozencore

When set to "true" the frozen core approximation is applied, i.e., the core states are fixed to the atomic states.

Attribute: gmaxvr

Maximum length of |G| for expanding the interstitial density and potential.

Attribute: isgkmax

Species for which the muffin-tin radius will be used for calculating gkmax.

Attribute: ldapu

Type of LDA+U method to be used.

Attribute: lmaxapw

Angular momentum cut-off for the APW functions.

Attribute: lmaxinr

Close to the nucleus, the density and potential is almost spherical and therefore the spherical harmonic expansion can be truncated a low angular momentum. See also fracinr.

Attribute: lmaxmat

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

Attribute: lmaxvr

Angular momentum cut-off for the muffin-tin density and potential.

Attribute: lradstep

Some muffin-tin functions (such as the density) are calculated on a coarse radial mesh and then interpolated onto a fine mesh. This is done for the sake of efficiency. lradstp defines the step size in going from the fine to the coarse radial mesh. If it is too large, loss of precision may occur.

Attribute: maxscl

Upper limit for te selfconsistency loop.

Attribute: mixer

select the mixing (relaxation) scheme for SCF

Attribute: nempty

Defines the number of eigenstates beyond that required for charge neutrality. When running metals it is not known a priori how many states will be below the Fermi energy for each-point. Setting nempty greater than zero allows the additional states to act as a buffer in such cases. Furthermore, magnetic calculations use the first-variational eigenstates as a basis for setting up the second-variational Hamiltonian, and thus nempty will determine the size of this basis set. Convergence with respect to this quantity should be checked.

Attribute: ngridk

Number of k grid points along the basis vector directions.

Attribute: nosource

When set to "true" , source fields are projected out of the exchange-correlation magnetic field. experimental feature.

Attribute: nosym

When set to "true" no symmetries, apart from the identity, are used anywhere in the code.

Attribute: nprad

Smallest occupancy for which a state will contribute to the density.

Attribute: npsden

oOrder of polynomial for pseudocharge density.

Attribute: nwrite

Normally, the density and potentials are written to the file STATE.OUT only after com- pletion of the self-consistent loop. By setting nwrite to a positive integer the file will be written during the loop every nwrite iterations.

Attribute: ptnucl

The attrubute ptnucl is "true" if the nuclei are to be treated as point charges, if "false" the nuclei have a finite spherical distribution.

Attribute: radkpt

Used for the automatic determination of the-point mesh. If autokpt is set to "true" then the mesh sizes will be determined by$n_i=\lambda/|{ \bf A}_i|+1$.

Attribute: reducek

If the attribute reducek is "true" the$\bf{k}$-point set is reduced with the crystal symmetries.

Attribute: rgkmax

The parameter rgkmax implicitly determines the number of basis functions and is one of the crucial parameters for the accuracy of the calculation. It represents the product of two quantities:$R_{MT,\, Min}$, the smallest of all muffin-tin radii, and$|{ \bf G}+{ \bf k}|_{max}$, the maximum length for the${ \bf G}+{ \bf k}$\ vectors. Because each${ \bf G}+{ \bf k}$\ vector represents one basis function, rgkmax gives the number of basis functions used for solving the Kohn-Sham equations. Typical values of rgkmax are between 6 and 9. However, for systems with very short bond-lengths, significantly smaller values may be sufficient. This may especially be the case for materials containing carbon, where rgkmax may be 4.5-5, or hydrogen, where even values between 3 and 4 may be sufficient. In any case, a convergence check is indispensible for a proper choice of this parameter for your system!

Attribute: rmtapm

Parameters governing the automatic generation of the muffin-tin radii. When autormtis set to "true" , the muffin-tin radii are found automatically from the formula

where$Z_i$is the atomic number of the$i$th species,$\zeta$is stored in rmtapm(1) and the value which governs the distance between the muffin-tins is stored in rmtapm(2). When rmtapm(2) =1, the closest muffin-tins will touch.

Attribute: stype

A smooth approximation to the Dirac delta function is needed to compute the occupancies of the Kohn-Sham states. The attribute swidth determines the width of the approximate delta function.

Attribute: swidth

Width of the smooth approximation to the Dirac delta function.

Attribute: tevecsv

The attribute tevecsv is "true" if second-variational eigenvectors are calculated.

Attribute: tfibs

Because calculation of the incomplete basis set (IBS) correction to the force is fairly time- consuming, it can be switched off by setting tfibs to "false" This correction can then be included only when necessary, i.e. when the atoms are close to equilibrium in a structural relaxation run.

Attribute: tforce

Decides if the force should be calculated at the end of the self-consistent cycle.

Attribute: vkloff

The k-point offset vector in lattice coordinates.

Attribute: xctype

Type of exchange-correlation functional to be used

• No exchange-correlation funtional ($E_{\rm xc}\equiv 0$)
• LDA, Perdew-Zunger/Ceperley-Alder, Phys. Rev. B 23 , 5048 (1981)
• LSDA, Perdew-Wang/Ceperley-Alder, Phys. Rev. B 45 , 13244 (1992)
• LDA, X-alpha approximation, J. C. Slater, Phys. Rev. 81 , 385 (1951)
• LSDA, von Barth-Hedin, J. Phys. C 5 , 1629 (1972)
• GGA, Perdew-Burke-Ernzerhof, Phys. Rev. Lett. 77 , 3865 (1996)
• GGA, Revised PBE, Zhang-Yang, Phys. Rev. Lett. 80 , 890 (1998)
• GGA, PBEsol, arXiv:0707.2088v1 (2007)
• GGA, Wu-Cohen exchange (WC06) with PBE correlation, Phys. Rev. B 73 , 235116 (2006)
• GGA, Armiento-Mattsson (AM05) spin-unpolarised functional, Phys. Rev. B 72 , 085108 (2005)

If the spin element is present calculation is done with spin polarization.

List of attributes: momfix , bfieldc , spinorb , spinsprl , vqlss , taufsm , reducebf , fixspin

Attribute: bfieldc

Alows to apply a constant B field This is a constant magnetic field applied throughout the entire unit cell and enters the second-variational Hamiltonian as

where$g_e$is the electron$g$-factor (2.0023193043718). This field is normally used to break spin symmetry for spin-polarised calculations and considered to be infinitesimal with no direct contribution to the total energy. In cases where the magnetic field is finite (for example when computing magnetic response) the external${ \bf B}$-field energy reported in INFO.OUT should be added to the total by hand. This field is applied throughout the entire unit cell. To apply magnetic fields in particular muffin-tins use the bfcmt vect ors in the atoms block. Collinear calculations are more efficient if the field is applied in the$z$-direction.

Attribute: fixspin

Attribute: momfix

The desired total moment for a FSM calculation.

Attribute: reducebf

After each iteration the external magnetic fields are multiplied with reducebf. This al- lows for a large external magnetic field at the start of the self-consistent loop to break spin symmetry, while at the end of the loop the field will be effectively zero, i.e. infinitesimal. See bfieldcand atom element.

Attribute: spinorb

If spinorb is "true" , then a$\boldsymbol \sigma\cdot{ \bf L}$term is added to the second-variational Hamiltonian.

Attribute: spinsprl

Set to "true" if a spin-spiral calculation is required. Experimental feature for the calculation of spin-spiral states. See vqlssfor details.

Attribute: taufsm

Attribute: vqlss

Is the${ \bf q}$-vector of the spin-spiral state in lattice coordinates. Spin-spirals arise from spinor states assumed to be of the form

These are determined using a second-variational approach, and give rise to a magnetization density of the form

where$m_x$,$m_y$and$m_z$are lattice periodic. See also spinprl.

Optional configuration options for eigenvector solver.

List of attributes: type , packedmatrixstorage , epsarpack , evaltol

Attribute: epsarpack

Tolerance parameter for the ARPACK shift invert solver

Attribute: evaltol

Error tolerance for the first-variational eigenvalues using the LAPACK Solver

Attribute: packedmatrixstorage

In the default calculation the matrix is sored in packed form. When using multithreaded BLAS setting this parmeter to "false" increases efficiency.

Attribute: type

Selects the eigenvalue solver for the first variational equation

The structure optimization element triggers if present a geometry relaxation.

List of attributes: epsforce , tau0atm , resume

Attribute: epsforce

Convergence tolerance for the forces during a structural optimization run.

Attribute: resume

Resumption of structural optimization run using density in STATE.OUT but with positions from input.xml .

Attribute: tau0atm

The step size to be used for structural optimization

The position of atom$\alpha$is updated on step$m$of a structural optimization run using

where$\tau_{\alpha}$is set to tau0atm for$m=0$, and incremented by the same amount if the atom is moving in the same direction between steps. If the direction changes then$\tau_{\alpha}$is reset to tau0atm .

Properties listed in this element can be calculated from the groundstate. It works also from a saved state from a previous run.

If present a banstructure is calculated.

List of attributes: scissor , character

Attribute: character

Band structure plot which includes angular momentum characters for every atom.

Attribute: scissor

Value to shift bandgap.

Wavefunction plot.

If present a DOS calculation is started.

DOS and optics plots require integrals of the kind

These are calculated by first interpolating the functions$e({ \bf k})$and$f({ \bf k})$with the trilinear method on a much finer mesh whose size is determined by ngrdos . Then the$\omega$-dependent histogram of the integrand is accumulated over the fine mesh. If the output function is noisy then either ngrdos should be increased or nwdos decreased. Alternatively, the output function can be artificially smoothed up to a level given by nsmdos . This is the number of successive 3-point averages to be applied to the function$g$.

List of attributes: sqados , lmirep , nwdos , ngrdos , nsmdos , winddos , scissor

Attribute: lmirep

When lmirep is set to "true" , the spherical harmonic basis is transformed into one in which the site symmetries are block diagonal. Band characters determined from the density matrix expressed in this basis correspond to irreducible representations, and allow the partial DOS to be resolved into physically relevant contributions, for example eg and t2g.

Attribute: ngrdos

Effective k-point mesh size to be used for Brillouin zone integration.

Attribute: nsmdos

Level of smoothing applied to DOS/optics output integer 0.

Attribute: nwdos

Number of frequency/energy points in the DOS

Attribute: scissor

Attribute: sqados

Spin-quantization axis in Cartesian coordinates used when plotting the spin-resolved DOS (z-axis by default).

Attribute: winddos

Frequency/energy window for the DOS or optics plot.

Output L, S and J expectation values.

Compute the effective mass tensor at the-point given by vklem.

List of attributes: deltaem , ndspem , vklem

Attribute: deltaem

The size of the k-vector displacement used when calculating numerical derivatives for the effective mass tensor.

Attribute: ndspem

The number of k-vector displacements in each direction around vklem when computing the numerical derivatives for the effective mass tensor.

Attribute: vklem

The k-point in lattice coordinates at which to compute the effective mass tensors.

Plot the charge density

Exchange-correlation and Coulomb potential plots.

Electron localization function (ELF).

Plot of magnetization vector field.

Plot of exchange-correlation magnetic vector field.

Writes the electric field to file.

Plot of he gradient of the magnetic vector field.

Writes Fermi surface data to file.

List of attributes: nstfsp , separate

Attribute: nstfsp

Number of states to be included in the Fermi surface plot file.

Attribute: separate

Calculation of electric field gradient (EFG), contact charge.

Linear optical response tensor.

List of attributes: scissor

Attribute: scissor

The components of the first- or second-order optical tensor to be calculated.

List of attributes: vecql

Attribute: vecql

Gives the q-vector in lattice coordinates for calculating ELNES.

List of attributes: mustar

Attribute: mustar

Coulomb pseudopotential, μ*, used in the McMillan-Allen-Dynes equation.

Phonon frequencies and eigen vectors for an arbitrary q-point.

List of attributes: do , ngridq , reduceq , deltaph

Attribute: deltaph

Phonon calculations are performed by constructing a supercell corresponding to a particular${\bf q}$-vector and making a small periodic displacement of the atoms. The magnitude of this displacement is given by deltaph. This should not be made too large, as anharmonic terms could then become significant, neither should it be too small as this can introduce numerical error.

Attribute: do

Decides if the phonon calculation is skipped or recalculated or continued from file.

Attribute: ngridq

Number of q grid points along the basis vector directions.

Attribute: reduceq

The attribute reduceq is set to "true" if the$q$-point set is to be reduced with the crystal symmetries.

Phonon density of states.

Phonon dispersion plot.

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).

List of attributes: emattype , dfoffdiag , lmaxapwwf , lmaxemat , emaxdf , broad , epsdfde , tevout , xstype , symmorph , fastpmat , fastemat , gather , tappinfo , dbglev , usegdft , gqmax , nosym , ngridk , vkloff , reducek , ngridq , reduceq , rgkmax , swidth , lmaxapw , lmaxmat , nempty , scissor

Attribute: broad

Lorentzian broadening for all spectra

Attribute: dbglev

Attribute: dfoffdiag

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

Attribute: emattype

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

Attribute: emaxdf

energy cutoff for the unoccupied states in the Kohn-Sahm response function and screening

Attribute: epsdfde

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

Attribute: fastemat

if "true" , a fast method to calculate APW-lo, lo-APW and lo-lo parts of the${\bf q}$-dependent matrix elements in the muffin-tin is used.

Attribute: fastpmat

if "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.

Attribute: gather

Attribute: gqmax

|G+q| cutoff for Kohn-Sham response function, screening and for expansion of Coulomb potential

Attribute: lmaxapw

angular momentum cut-off for the APW functions

Attribute: lmaxapwwf

maximum angular momentum for APW functions for q-dependent matrix elements

Attribute: lmaxemat

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

Attribute: lmaxmat

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

Attribute: nempty

number of empty states

Attribute: ngridk

k-point grid sizes

Attribute: ngridq

q-point grid sizes

Attribute: nosym

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

Attribute: reducek

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

Attribute: reduceq

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

Attribute: rgkmax

smallest muffin-tin radius times gkmax

Attribute: scissor

scissors correction