K MULTIPLY: Difference between revisions
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By default, {{TAG|LDOWNSAMPLE}} triggers an automatic search that tries the ''same'' multiplier in all three directions. This works for isotropic grids but fails for anisotropic ones, e.g., when the {{FILE|WAVECAR}} contains a 24×24×1 grid and the current calculation uses a 2×2×1 grid (requiring multipliers 12, 12, 1). In such cases, {{TAG|K_MULTIPLY}} must be set explicitly. | By default, {{TAG|LDOWNSAMPLE}} triggers an automatic search that tries the ''same'' multiplier in all three directions. This works for isotropic grids but fails for anisotropic ones, e.g., when the {{FILE|WAVECAR}} contains a 24×24×1 grid and the current calculation uses a 2×2×1 grid (requiring multipliers 12, 12, 1). In such cases, {{TAG|K_MULTIPLY}} must be set explicitly. | ||
{{NB| tip | For isotropic grids the automatic search is fast and {{TAG|K_MULTIPLY}} is not required. Use {{TAG|K_MULTIPLY}} when the grid ratio differs between directions.}} | {{NB| tip | For isotropic grids the automatic search is fast and {{TAG|K_MULTIPLY}} is not required. Use {{TAG|K_MULTIPLY}} when the grid ratio differs between directions.}} | ||
{{Available|6. | {{Available|6.6.1}} | ||
==Usage== | ==Usage== | ||
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Each value specifies the multiplier for the first, second, and third reciprocal-lattice direction, respectively. This is required when the dense-to-coarse grid ratio is not the same in every direction. | Each value specifies the multiplier for the first, second, and third reciprocal-lattice direction, respectively. This is required when the dense-to-coarse grid ratio is not the same in every direction. | ||
{{NB| warning | All values must be positive integers. Providing any number of values other than 1 or 3 will cause an error.}} | {{NB| warning | All values must be positive integers. Providing any number of values other than 1 or 3 will cause an error.}} | ||
== Related tags and articles== | == Related tags and articles== | ||
{{TAG|LDOWNSAMPLE}} | {{TAG|LDOWNSAMPLE}} | ||
Latest revision as of 16:08, 17 April 2026
K_MULTIPLY = [integer array]
| Default: K_MULTIPLY | = -1 -1 -1 | if not set in INCAR |
Description: K_MULTIPLY sets the per-direction k-point grid multiplier for downsampling from a denser WAVECAR
K_MULTIPLY specifies the ratio between the denser k-point grid stored in the WAVECAR (or vaspwave.h5) and the coarser grid of the current calculation, for each of the three reciprocal-lattice directions independently.
When K_MULTIPLY is set, LDOWNSAMPLE is automatically set to LDOWNSAMPLE = .TRUE..
By default, LDOWNSAMPLE triggers an automatic search that tries the same multiplier in all three directions. This works for isotropic grids but fails for anisotropic ones, e.g., when the WAVECAR contains a 24×24×1 grid and the current calculation uses a 2×2×1 grid (requiring multipliers 12, 12, 1). In such cases, K_MULTIPLY must be set explicitly.
| Tip: For isotropic grids the automatic search is fast and K_MULTIPLY is not required. Use K_MULTIPLY when the grid ratio differs between directions. |
| Mind: Available as of VASP 6.6.1 |
Usage
Single value
K_MULTIPLY = 2
The value is replicated to all three directions, equivalent to K_MULTIPLY = 2 2 2.
Three values (anisotropic)
K_MULTIPLY = 12 12 1
Each value specifies the multiplier for the first, second, and third reciprocal-lattice direction, respectively. This is required when the dense-to-coarse grid ratio is not the same in every direction.
| Warning: All values must be positive integers. Providing any number of values other than 1 or 3 will cause an error. |