The Fleur input file
Fleur expects all input (execpt some computational settings specified on the command line) in the inp.xml file
in the current working directory. This file is usually produced by the input-generator 'inpgen' but
Fleur workflows require adjustments to this file.
Example inp.xml file
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<fleurInput fleurInputVersion="0.33">
<comment>
Si bulk
</comment>
<calculationSetup>
<cutoffs Kmax="3.70" Gmax="11.10" GmaxXC="9.20" numbands="0"/>
<scfLoop itmax="15" minDistance=".00001" maxIterBroyd="99"
imix="Anderson" alpha=".05" precondParam="0.0" spinf="2.0"/>
<coreElectrons ctail="T" frcor="F" kcrel="0" coretail_lmax="0"/>
<magnetism jspins="1" l_noco="F" swsp="F" lflip="F"/>
<soc theta=".00000000" phi=".00000000" l_soc="F" spav="F"/>
<expertModes gw="0" secvar="F"/>
<geometryOptimization l_f="F" forcealpha="1.00" forcemix="BFGS"
epsdisp=".00001" epsforce=".00001"/>
<ldaU l_linMix="F" mixParam=".050000" spinf="1.000000"/>
<xcFunctional name="pbe" relativisticCorrections="F"/>
</calculationSetup>
<cell>
<bzIntegration valenceElectrons="20.00000000" mode="hist"
fermiSmearingEnergy=".00100000">
<KPointListSelection Listname="Default" />
<KPointLists>
<KPointList Name="Default" Count="2" Type="Path">
<kPoint weight="0.050000">0.025000 0.0 0.0</kPoint>
<kPoint weight="0.050000">0.450000 0.0 0.0</kPoint>
<kPoint weight="0.050000" label="myPoint">0.475000 0.0 0.0</kPoint>
</kPointList>
</kPointLists>
</bzIntegration>
<symmetryOperations>
<symOp>
<row-1>1 0 0 .0000000000</row-1>
<row-2>0 1 0 .0000000000</row-2>
<row-3>0 0 1 .0000000000</row-3>
</symOp>
</symmetryOperations>
<bulkLattice scale="1.0000000000" latnam="any">
<bravaisMatrix>
<row-1>.0000000000 5.1306085335 5.1306085335</row-1>
<row-2>5.1306085335 .0000000000 5.1306085335</row-2>
<row-3>5.1306085335 5.1306085335 .0000000000</row-3>
</bravaisMatrix>
</bulkLattice>
</cell>
<atomSpecies>
<species name="Si-1" element="Si" atomicNumber="14">
<mtSphere radius="2.16000000" gridPoints="521" logIncrement=".02200000"/>
<atomicCutoffs lmax="8" lnonsphr="6"/>
<electronConfig>
<coreConfig>(1s1/2) (2s1/2) (2p1/2) (2p3/2) </coreConfig>
<valenceConfig>(3s1/2) (3p1/2)</valenceConfig>
</electronConfig>
<energyParameters s="3" p="3" d="3" f="4"/>
</species>
</atomSpecies>
<atomGroups>
<atomGroup species="Si-1">
<relPos label=" 1">1.00/8.00 1.00/8.00 1.00/8.00</relPos>
<relPos label=" 2">-1.00/8.00 -1.00/8.00 -1.00/8.00</relPos>
<force calculate="T" relaxXYZ="TTT"/>
</atomGroup>
</atomGroups>
<output dos="F" band="F" slice="F" >
<checks vchk="F" cdinf="F"/>
<bandDOS minEnergy="-.50" maxEnergy=".50"
sigma=".0150"/>
<vacuumDOS layers="0" integ="F" star="F" nstars="0" locx1=".00000"
locy1=".00000" locx2=".00000" locy2=".00000" nstm="0"
tworkf=".00000"/>
<unfoldingBand unfoldBand="F" supercellX="1"
supercellY="1" supercellZ="1"/>
<plotting iplot="0" />
<chargeDensitySlicing numkpt="0" minEigenval=".00000"
maxEigenval=".00000" nnne="0" pallst="F"/>
<specialOutput eonly="F" bmt="F"/>
<magneticCircularDichroism mcd="F" energyLo="-10.0000" energyUp=".0000"/>
</output>
<!-- We include the file relax.inp here to enable relaxations
(see documentation) -->
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
href="relax.xml">
<xi:fallback/>
</xi:include>
</fleurInput>
Being an XML file inp.xml starts with some general XML information in line 1. The rest of the file is enclosed in
the <fleurInput> element that carries as an attribute the version number of the input file format. Within <fleurInput> the
input file consists of several sections to be discussed in detail below.
Comment and Constants sections
<comment>
Si bulk
</comment>
The comment section is optional. It encloses a simple line of text that is written out as part of the inp.xml into the out.xml file.
<constants>
<constant name="myConst" value="5.1673552752"/>
</constants>
The constants section is optional and not part of the example inp.xml file shown above. It can be used to define constants
that can then be used in other parts of the XML input file, e.g., the lattice setup or the declaration of the atom positions.
The constants element may enclose multiple constant definitions. Each one has to provide the name and value of the respective constant.
Calculation Setup section
<calculationSetup>
<cutoffs Kmax="3.70" Gmax="11.10" GmaxXC="9.20" numbands="0"/>
<scfLoop itmax="15" minDistance=".00001" maxIterBroyd="99"
imix="Anderson" alpha=".05" precondParam="0.0" spinf="2.0"/>
<coreElectrons ctail="T" frcor="F" kcrel="0" coretail_lmax="0"/>
<magnetism jspins="1" l_noco="F" swsp="F" lflip="F"/>
<soc theta=".00000000" phi=".00000000" l_soc="F" spav="F"/>
<expertModes gw="0" secvar="F"/>
<geometryOptimization l_f="F" forcealpha="1.00" forcemix="BFGS"
epsdisp=".00001" epsforce=".00001"/>
<ldaU l_linMix="F" mixParam=".050000" spinf="1.000000"/>
<xcFunctional name="pbe" relativisticCorrections="F"/>
</calculationSetup>
The calculation setup section covers the input of general numerical parameters controlling the Fleur calculation.
| Tag | Attribute | Description |
|---|---|---|
| cutoffs | The main cutoff parameters for the calculation | |
| Kmax | The cutoff for the basis functions | |
| Gmax | The cutoff for the density | |
| GmaxXC | The cutoff used for the potential when the XC functional is calculated | |
| numbands | The number of eigenvalues to be calculated at each k point. A value of 0 is converted to a default value. | |
| scfLoop | Parameters controlling the number of SCF loop iterations and the mixing scheme | |
| itmax | The number of SCF loop iterations to be performed by Fleur | |
| maxIterBroyd | The number of iterations to be taken into account by Broyden-like mixing schemes. The mixing history is periodically deleted with the periodicity specified by this parameter. | |
| imix | The mixing scheme. This can be one of "straight", "Broyden1", "Broyden2", and "Anderson" | |
| alpha | The mixing factor | |
| precondParam | The preconditioning parameter for bulk metals. Typical value: 0.8. Choose higher mixing parameter, e.g. 0.25. | |
| spinf | The spin mixing factor enhancement | |
| coreElectrons | Parameters for the treatment of the core electrons | |
| ctail | Use core tail corrections. | |
| frcor | The frozen core approximation can be activated here. | |
| kcrel | If true fully relativistic core routines are used, otherwise only spin-polarized routines. | |
| coretail_lmax | Cutoff for the expansion of the core-tail into other MT spheres. Also relevant for initial charge generation. | |
| magnetism | Parameters for controlling the degree of magnetism considered in the calculation | |
| jspins | The number of spins to be considered: 1 for nonmagnetic calculations and 2 for calculations incorporating magnetism. | |
| l_noco | Set this to true to consider not only collinear but also non-collinear magnetism | |
| See the section on the non-collinear magnetism setup for details. | ||
| swsp | If true generate spin-polarized from unpolarized density. | |
| lflip | If true flip spin directions for each atom with set flipSpin flag. | |
| soc | Parameters needed for calculations with spin-orbit coupling | |
| theta | The spin quantization axis is given by the theta and phi angles. | |
| phi | The spin quantization axis is given by the theta and phi angles. | |
| l_soc | This switch is used to toggle the consideration of spin-orbit coupling in the respective calculation . | |
| spav | Construct spin-orbit operator from spin-averaged potential. | |
| expertModes | Parameters for the control of certain advanced Fleur calculation modes | |
| gw | The different output modes for GW approximation calculations are set here. | |
| secvar | Treat the nonspherical part of the Hamiltonian in second variation. | |
| geometryOptimization | Parameters required for force calculations and the optimization of atom positions | |
| l_f | l_f is used to switch on the calculation of forces. | |
| forcealpha | The mixing parameter for the forces when performing structural optimizations. | |
| forcemix | The mixing procedure for the forces. Choose one of "BFGS" and "straight" | |
| epsdisp | The convergence criterion for atom displacements. | |
| epsforce | The convergence criterion for the forces. | |
| For further options on relaxation.. | ||
| ldaU | Optional parameters for the density matrix mixing in LDA+U calculations. See the LDA+U setup for details. | |
| xcFunctional | see below |
The exchange correlation functional section consists of a single xml element with the two attributes name and
relativisticCorrections. The XC functional is specified by the name attribute:
| LDA functionals | |
|---|---|
| x-a | |
| wign | |
| mjw | |
| pz | The functional by Perdew and Zunger |
| vwn | The functional by Vosko, Wilk, and Nusair |
| bh | The functional by Barth and Hedin |
| GGA functionals | |
|---|---|
| pw91 | The functional by Perdew and Wang |
| pbe | The functional by Perdew, Burke, and Ernzerhof |
| rpbe | The revPBE functional by Zhang and Yang |
| Rpbe | The RPBE functional by Hammer, Hansen, and Nørskov |
| wc | The functional by Wu and Cohen |
| Tag | Attribute | Description |
|---|---|---|
| relativisticCorrections | A boolean switch used to activate optional relativistic corrections according to MacDonnald-Vosko. |
Cell section
<cell>
<bzIntegration valenceElectrons="20.00000000" mode="hist"
fermiSmearingEnergy=".00100000">
<KPointListSelection Listname="Default" />
<KPointLists>
<KPointList Name="Default" Count="2" Type="Path">
<kPoint weight="0.050000">0.025000 0.0 0.0</kPoint>
<kPoint weight="0.050000">0.450000 0.0 0.0</kPoint>
<kPoint weight="0.050000" label="myPoint">0.475000 0.0 0.0</kPoint>
</kPointList>
</kPointLists>
</bzIntegration>
<symmetryOperations>
<symOp>
<row-1>1 0 0 .0000000000</row-1>
<row-2>0 1 0 .0000000000</row-2>
<row-3>0 0 1 .0000000000</row-3>
</symOp>
</symmetryOperations>
<bulkLattice scale="1.0000000000" latnam="any">
<bravaisMatrix>
<row-1>.0000000000 5.1306085335 5.1306085335</row-1>
<row-2>5.1306085335 .0000000000 5.1306085335</row-2>
<row-3>5.1306085335 5.1306085335 .0000000000</row-3>
</bravaisMatrix>
</bulkLattice>
</cell>
The cell section covers the declaration of the k-points, of the symmetry operations available in the unit cell and the definition of the lattice vectors. For details please see the sections on the kpoint setup, Bravais lattice setup and the unit cell symmetry setup.
Atom species section
<atomSpecies>
<species name="Si-1" element="Si" atomicNumber="14">
<mtSphere radius="2.16000000" gridPoints="521" logIncrement=".02200000"/>
<atomicCutoffs lmax="8" lnonsphr="6"/>
<electronConfig>
<coreConfig>(1s1/2) (2s1/2) (2p1/2) (2p3/2) </coreConfig>
<valenceConfig>(3s1/2) (3p1/2)</valenceConfig>
</electronConfig>
<energyParameters s="3" p="3" d="3" f="4"/>
</species>
</atomSpecies>
The atomSpecies section is a tool to set identical numerical parameters for the atoms of different atom groups
without introducing redundancy. For this several species with a unique name can be defined in the section. In
the following atomGroups section each atom group is associated to one of the species.
| Tag | Attribute | Description |
|---|---|---|
| species | The element defining a species. There can be multiple of these elements in this section. | |
| name | A name for the species. This should be unique within the set of species. | |
| element | The abbreviation of the chemical element. | |
| atomicNumber | The atomic number of the chemical element. |
A species element contains other elements to determine its numerical parameters. Please note that the order of these elements in the input file is predefined:
| Tag | Attribute | Description |
|---|---|---|
| mtSphere | This element is used to define the properties of the muffin-tin spheres. | |
| radius | The radius of the MT sphere. | |
| gridPoints | The number of grid points on the radial mesh for this MT sphere. | |
| logIncrement | The logarithmic increment of the radial mesh. | |
| atomicCutoffs | This element covers the l-cutoffs. | |
| lmax | The general l-cutoff for all atoms of the species. | |
| lnonsphr | The reduced l-cutoff for the calculation of contributions originating from non-spherical part of the potential | |
| lmaxAPW | If present the APW+lo approach will be used. This is the cutoff defining the lmax up to which LAPWs are used if no APW+lo local orbital is defined for the respective l. See also the respective article by G.K.H. Madsen. | |
| energyParameters | This element sets the energy parameters. | |
| s | The main quantum number for the valence s electrons. | |
| p | The main quantum number for the valence p electrons. | |
| d | The main quantum number for the valence d electrons. | |
| f | The main quantum number for the valence f electrons. | |
| special | ||
| socscale | A float in range from 0.0 to 1.0. Scales the magnitude of SOC at the species. socscale="0.0" switches SOC off. | |
| vca_charge | A float to specify an extra charge for calculations in the virtual crystal approximation for this species. | |
| lda | Logical switch to use LDA for this atom. | |
| b_field_mt | Zeeman field applied to this atom. | |
| electronConfig | See the description of the electron configuration setup for details. | |
| ldaU | Up to one ldaU element can be present to define a U parameter for this atom and a certain l channel. | |
| l | This is the l channel the U is supposed to affect. | |
| U | This is the U parameter in eV. | |
| J | This is the J parameter in eV. | |
| l_amf | If true the around mean field limit is employed, otherwise the atomic limit. | |
| For a more detailed description have a look at [[xmlLDAUSetup | ||
| lo | This element is used to introduce local orbitals to each of the associated atoms. It can be present multiple times. See the section on the local orbital setup for a more profound discussion. | |
| type | The type of the LO. This can be SCLO for semicore LOs or HELO for LOs at higher energies | |
| l | The angular momentum quantum number belonging to this LO | |
| n | The main quantum number for this LO | |
| eDeriv | The energy derivative of the additional radial function introduced with this LO. This is by default 0 to obtain conventional LOs. For HDLOs it has to be set to a finite positive integer value. |
Atom groups section
<atomGroups>
<atomGroup species="Si-1">
<relPos label=" 1">1.00/8.00 1.00/8.00 1.00/8.00</relPos>
<relPos label=" 2">-1.00/8.00 -1.00/8.00 -1.00/8.00</relPos>
<force calculate="T" relaxXYZ="TTT"/>
</atomGroup>
</atomGroups>
The atom groups section covers parameters relevant for each group of symmetry equivalent atoms.
| Tag | Attribute | Description |
|---|---|---|
| atomGroup | There is at least one atom group. Each atom in the unit cell has to be in one. | |
| species | The name of the species of this group's atoms. |
Each atom group element encloses certain other elements:
| Tag | Attribute | Description |
|---|---|---|
| relPos | See below | |
| filmPos | See below | |
| force | Some switches associated to force calculations. | |
| calculate | This boolean switch determines whether forces are calculated for the atoms of this group. | |
| relaxXYZ | Three boolean switches used declare in which directions the atom position may be optimized in force relaxation calculations. | |
| nocoParams | See the description of the non-collinear magnetism setup for details. |
The atom positions are defined within each atomGroup of symmetry equivalent atoms in the atom groups section of the input file. They can be provided as relative or film positions:
Relative positions
<atomGroup species="W-1">
<relPos label=" 1">.000000 1.0/2.0 .060000</relPos>
<relPos label=" 2">1.0/2.0 .000000 -.060000</relPos>
<force calculate="T" relaxXYZ="TTT"/>
</atomGroup>
Typically for bulk materials the atom positions are provided in relative coordinates as fractions of the three lattice vectors.
For this the relPos tag is used. In the example the atom group consists of two atoms at two different positions. The
first one is the representative atom. As shown the relative coordinates are provided as three numbers within the relPos
element. Note that each coordinate can also be provided by a short mathematical expression that does not contain any
spaces, e.g., 1.0/4.0.
Each atom can be associated to a label that can be specified in the inpgen input. If there is no explicit labeling in the inpgen
input the labels just associate a unique number with each atom. This labeling is only meant as a help to the user to keep an overview
for setups of very large unit cells.
Film positions
<atomGroup species="W-2">
<filmPos label=" 1">1.0/2.0 1.0/2.0 -12.0314467594</filmPos>
<filmPos label=" 2">1.0/2.0 1.0/2.0 12.0314467594</filmPos>
<force calculate="T" relaxXYZ="TTT"/>
</atomGroup>
For calculations on films the atom positions are provided within the filmPos element. Here, the first two of the coordinates are relative, while the third coordinate in the direction normal to the film plane is absolute and in atomic units (Bohr radii).
Output section
<output dos="F" band="F" slice="F" >
<checks vchk="F" cdinf="F"/>
<bandDOS minEnergy="-.50" maxEnergy=".50"
sigma=".0150"/>
<vacuumDOS layers="0" integ="F" star="F" nstars="0" locx1=".00000"
locy1=".00000" locx2=".00000" locy2=".00000" nstm="0"
tworkf=".00000"/>
<unfoldingBand unfoldBand="F" supercellX="1"
supercellY="1" supercellZ="1"/>
<plotting iplot="0" />
<chargeDensitySlicing numkpt="0" minEigenval=".00000"
maxEigenval=".00000" nnne="0" pallst="F"/>
<specialOutput eonly="F" bmt="F"/>
<magneticCircularDichroism mcd="F" energyLo="-10.0000" energyUp=".0000"/>
</output>
The output section is optional. It covers parameters relevant for the generation of special output.
| Tag | Attribute | Description |
|---|---|---|
| output | ||
| dos | A boolean switch that determines whether a density of states has to be calculated. | |
| band | A boolean switch that determines whether a band structure calculation should be performed. | |
| slice | A boolean switch controlling whether a slice has to be calculated. The associated parameters are set in the chargeDensitySlicing element. |
If an attribute of the output element is set to true the associated enclosed element has to be present:
| Tag | Attribute | Description |
|---|---|---|
| checks | The checks element covers several switches to perform and write out certain tests. | |
| vchk | Continuity checks of the potential at the MT and vacuum boundaries. | |
| cdinf | Calculation of partial charges and the continuity of the density. | |
| disp | Calculation of the distance between the in- and output potential. | |
| bandDOS | Select the DOS calculation mode. For details have a look at the respective section. | |
| vacuumDOS | For details have a look at the respective section. | |
| unfoldingBand | ||
| unfoldBand | A boolean switch that defines if unfolding is used and additional weights are written. | |
| supercellX | The size of the supercell (in units of simple unit cells) (iteger value) in X direction. | |
| supercellY | The size of the supercell (in units of simple unit cells) (iteger value) in Y direction. | |
| supercellZ | The size of the supercell (in units of simple unit cells) (iteger value) in Z direction. | |
| plotting | The plotting element groups several switches to plot the density and the potential. | |
| iplot | Calculate a charge density plot. For details see the respective section. | |
| score | If true the core charge is excluded from the plot. | |
| plplot | This switch allows the plotting of the potential from its respective files. | |
| chargeDensitySlicing | ||
| numkpt | This is the number of the k-point which is used for the slice (k=0 : all k-points are used) | |
| minEigenval | This is the lower boundary for eigenvalues in the slice. | |
| maxEigenval | This is the upper boundary for eigenvalues in the slice. | |
| nnne | The number of eigenvalues used for the slice (nnne=0 : all eigenvalues between boundaries are taken into account) | |
| pallst | Set this to true if states above the Fermi level are plotted. | |
| coreSpectrum | See the section on core spectrum calculations for details. | |
| magneticCircularDichroism | See the section on magnetic circular dichroism calculations for details. |
Force therorem section
<forceTheorem>
<MAE theta="0.0 0.1*Pi" phi="0.0 0.2*Pi" />
</forceTheorem>
It is possible to apply the magnetic force theorem to perform efficient approximative calculations on the magnetocrystalline
anisotropy energy (MAE), spin-spiral dispersions, the Dzyaloshinskii Moriya interaction (DMI), and the Heisenberg exchange interaction.
To do so a forceTheorem section has to be inserted directly below the output section. For details see the section on
the respective calculations.
Inclusion of the relax.xml file
<!-- We include the file relax.inp here to enable relaxations
(see documentation) -->
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
href="relax.xml">
<xi:fallback/>
</xi:include>
It is possible to automatically include other xml files into the Fleur input file by using the respective XInclude feature.
By default this is done for the relax.xml file. The syntax above also provides a fallback that is used when the
relax.xml file is not present: In that case it is just not included, but a message about this is written out to the
terminal.
When starting new Fleur calculations the relax.xml file is typically not present. It is automatically created when
geometry optimizations for the atom positions are performed. Its contents are the atom displacements calculated so far. These
automatically modify the atom positions provided in the Fleur input file. Furthermore a history of atom positions and
related forces for the previous optimization steps is found in the relax.xml file. This is needed for the determination
of the next displacements for ongoing atom position optimization calculations.
Details on how geometry optimizations are performed are found in the respective section.