k-point set setup

In the FLEUR inp.xml file you typically find a series of XML-tags like this the cell section:

<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            0.000000            0.000000</kPoint>
     <kPoint weight="0.050000">0.450000            0.000000            0.000000</kPoint>
    </Kpointlist>
   </kPointLists>
</bzIntegration>

Alternatively, the KpointLists might be put into a separate kpts.xml file and in the inp.xml you find the corresponding include.

<bzIntegration valenceElectrons="20.00000000" mode="hist" fermiSmearingEnergy=".00100000">
   <Kpointlistselection Listname="Default" />
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="kpts.xml">
</bzIntegration>

Brillouin zone integration

The highest level tag to be found is the bzIntegration tag:

Attribute	Desciption
valenceElectrons	The total number of valence electrons in your system
mode	Method to determine the Fermi level. Supported are:
	hist - Use the histogram mode. This is the default.
	gauss - Use Gaussian smearing.
	tria - Use the tetrahedron method.
fermiSmearingEnergy	The Fermi smearing can be parametrized by this energy in Hartree.
fermiSmearingTemp	As an alternative to fermiSmearingEnergy a Fermi smearing temperature can be set in Kelvin.

Selecting a k-point set

Then, the Kpointlistselection tag with a single attribute Listname is used to select the k-point set from the List provided. The Listname has to correspond to a Name attribute of one of the KpointLists.

The List of k-points

You might have different k-point sets in your setup, these KpointList XML elements are included into an outer KpointLists tag. Usually, the inpgen will generate multiple sets of k-points initially. With further calls to inpgen you might create further sets.

A Kpointlist is defined with the following attributes:

Attribute	Desciption
Name	Name of the k-point set to be used in Kpointlistselection. (required)
Count	Number of k-points in the set. (optional)
type	Description of the type: at present one of mesh,path,tria-bulk,tria,SPEX-mesh,unspecified (optional)
nx,ny,nz	Size of the mesh in three spatial directions. (optional)
nkq_pairs	Pairs of k,q vectors in a hybrid calculation. (optional)

Each kPoint element features the attribute weight and three numbers. The weight is the weight of the $\vec{k}$ point in the Brillouin zone integration. Each of the three numbers is divided by the value of the posScale attribute of the kPointList element to obtain the coordinates of the $\vec{k}$ point. In addition a label can be provided for use in bandstructure calculations.