Hi everyone,
I am using wien2k to calculte material properties. My quetion concern band calculation. In fact, How to choose K path or high symmetry points? Is there a unique choice for each space groupe?
Thanks
Choosing the k-points for a band structure calculation is an important step in determining the electronic properties of a material.
One way to choose k-points is to use a high-symmetry path in the BZ. High-symmetry points are special points in the BZ that are invariant under one or more symmetry operations of the crystal lattice. These points can be used to define a path through the BZ, and the band structure can be calculated along this path.
A common choice of high-symmetry points is the so-called "special k-points" that are determined by the space group of the crystal. Each space group has a unique set of special k-points, and this set can be used to define a high-symmetry path in the BZ. This path can be used to calculate the band structure of a material that belongs to that space group.
Another approach to choose k-points for band structure calculation is using a Monkhorst-Pack grid. This method uses a regular grid of k-points to sample the BZ, and it is especially useful for systems with large unit cells or complex Brillouin zones.
K points should be in such a way that you dont miss any special point. For a particular material you can take help from literature.
For ex: In case of graphene if you do not consider H or K symmetry point the band structure shows a gap because the bands in graphene meet along these points and if we miss these points then we are wrong.
When calculating the band structure of a crystal, it is important to choose a path or a set of high-symmetry points that will give you a representative sampling of the Brillouin zone. The choice of path or points depends on the symmetry of the crystal and the properties of the electronic structure that you want to study.
For simple crystals with high symmetry, such as the diamond or zincblende structures, there are well-defined high-symmetry points that are commonly used to calculate the band structure. These points are often referred to as the "special" or "high-symmetry" points and are typically located at the corners, edges, and centers of the Brillouin zone. In these cases, there is usually a unique choice of high-symmetry points that is appropriate for calculating the band structure.
For more complex crystals with lower symmetry, there may not be a unique choice of high-symmetry points, and it may be necessary to use a more general path in k-space to get a representative sampling of the Brillouin zone. In these cases, it is important to choose a path that covers a wide range of k-vectors and that includes important features of the electronic structure, such as band crossings or band gaps.
Overall, the choice of path or high-symmetry points depends on the crystal symmetry and the features of the electronic structure that you want to study. It is important to choose a path or set of points that provides a representative sampling of the Brillouin zone and that includes the important features of the electronic structure.
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