KSPACING

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KSPACING = [real]
Default: KSPACING = 0.5

Description: The tag KSPACING determines the number of k points if the KPOINTS file is not present.

KSPACING is the smallest allowed spacing between k points in units of $\mathrm {\AA} ^{-1}$ . The number of k points increases when the spacing is decreased. The number of k points in the direction of the first, second and third reciprocal lattice vector is determined by $N_{i}=\mathrm {max} (1,\mathrm {ceiling} (|\mathbf {b} _{i}|2\pi /\mathrm {KSPACING} ))$ with $\mathrm {ceiling} (x)$ being the ceiling function which returns the least integer that is equal or larger than $x$ . In this equation, $\mathbf {b} _{i}$ are the reciprocal lattice vectors $\mathbf {b} _{i}\mathbf {a} _{j}=\delta _{ij}$ . The generated grid is centered at the $\Gamma$ point if KGAMMA=True (default), i.e., includes the $\Gamma$ point. For KGAMMA=False, the grid is shifted away from the $\Gamma$ point as done for Monkhorst-Pack grids.

Mind: This implementation is not entirely identical with the deprecated automatic k-point generation used in the KPOINTS file.

If the k points are generated using the automatic mode in the KPOINTS file, $N_{i}$ is calculated as $N_{i}=\mathrm {int} (\mathrm {max} (1,R_{k}|\mathbf {b} _{i}|+0.5))$ with $R_{k}=2\pi /\mathrm {KSPACING}$ and rounding it to the nearest integer. We recommend using the KSPACING tag in the INCAR file and avoiding the automatic mode via the KPOINTS file.

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