# Generating a Gamma centered uniform k mesh in SIESTA DFT

The SIESTA DFT software provides to incorporate a Monkhorst-Pack k grid in DFT calculations. However to use the results with the BoltzTraP2 software, a Gamma centered k-grid with uniform distribution is required. Has anyone had any experience with this kind of a problem for 1D and 2D systems?

The siesta kgrid specification looks like this:

%block kgrid.MonkhorstPack
<int> <int> <int> <offset>
<int> <int> <int> <offset>
<int> <int> <int> <offset>
%endblock kgrid.MonkhorstPack


What $$\Gamma$$ centered means is that the offsets are all $$0.$$.
For some systems it may be beneficial to use non-centered grids to reduce the total number of k-points due to symmetries. However, if BoltzTraP2 requires the $$\Gamma$$ centered variant, simply do as above and set <offset> to $$0.$$ for each direction.

Here an example with NA, NB, NC being the number of k-points along each reciprocal lattice vector:

%block kgrid.MonkhorstPack
NA 0 0 0.
0 NB 0 0.
0 0 NC 0.
%endblock kgrid.MonkhorstPack


For details related to their meaning see here.

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