KERNEL TRUNCATION/LTRUNCATE: Difference between revisions
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Setting {{TAG|KERNEL_TRUNCATION/LTRUNCATE}} = T switches on the Coulomb-kernel-truncation method{{cite|vijay:prb:2025}}{{cite|rozzi:prb:2006}}{{cite|sohier:prb:2017}}. It effectively removes interactions with periodic replicas in non-periodic directions. In other words, the interactions are removed along the surface normal for [[2D materials]], and along all directions for 0D systems, i.e. for isolated atoms and molecules. | Setting {{TAG|KERNEL_TRUNCATION/LTRUNCATE}} = T switches on the Coulomb-kernel-truncation method{{cite|vijay:prb:2025}}{{cite|rozzi:prb:2006}}{{cite|sohier:prb:2017}}. It effectively removes interactions with periodic replicas in non-periodic directions. In other words, the interactions are removed along the surface normal for [[2D materials]], and along all directions for 0D systems, i.e. for isolated atoms and molecules. | ||
{{NB|important| Slabs must be centered in the unit cell.}} | {{NB|important| Slabs must be centered in the unit cell.}} | ||
In the simplest implementation of the Coulomb-kernel-truncation method ({{TAG|KERNEL_TRUNCATION/LCOARSEN|F}}), the computational cell provided in the {{FILE|POSCAR}} file is internally padded by an additional vacuum | In the simplest implementation of the Coulomb-kernel-truncation method ({{TAG|KERNEL_TRUNCATION/LCOARSEN|F}}), the computational cell provided in the {{FILE|POSCAR}} file is internally padded by an additional vacuum (see {{TAG|KERNEL_TRUNCATION/IPAD}}). This implies increasing the [[Energy cutoff and FFT meshes|FFT-grid sizes]] by a certain factor and thus leads to a significant increase in computational cost. | ||
{{NB|tip|Use the {{TAG|KERNEL_TRUNCATION/LCOARSEN|T}} to avoid the increased [[Energy cutoff and FFT meshes|FFT-grid sizes]].}} | {{NB|tip|Use the {{TAG|KERNEL_TRUNCATION/LCOARSEN|T}} to avoid the increased [[Energy cutoff and FFT meshes|FFT-grid sizes]].}} | ||
{{NB|mind| | {{NB|mind| | ||
Revision as of 10:57, 17 March 2026
KERNEL_TRUNCATION/LTRUNCATE = .True. | .False.
Default: KERNEL_TRUNCATION/LTRUNCATE = .False.
Description: Truncates the Coulomb kernel to remove electrostatic interactions along non-periodic dimensions.
Setting KERNEL_TRUNCATION/LTRUNCATE = T switches on the Coulomb-kernel-truncation method[1][2][3]. It effectively removes interactions with periodic replicas in non-periodic directions. In other words, the interactions are removed along the surface normal for 2D materials, and along all directions for 0D systems, i.e. for isolated atoms and molecules.
| Important: Slabs must be centered in the unit cell. |
In the simplest implementation of the Coulomb-kernel-truncation method (KERNEL_TRUNCATION/LCOARSEN = F), the computational cell provided in the POSCAR file is internally padded by an additional vacuum (see KERNEL_TRUNCATION/IPAD). This implies increasing the FFT-grid sizes by a certain factor and thus leads to a significant increase in computational cost.
Tip: Use the KERNEL_TRUNCATION/LCOARSEN = T to avoid the increased FFT-grid sizes.
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Mind:
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Detailed information about the setting are documented on respective related tags.
Related tags and articles
KERNEL_TRUNCATION/LCOARSEN, KERNEL_TRUNCATION/IDIMENSIONALITY, KERNEL_TRUNCATION/ISURFACE, KERNEL_TRUNCATION/FACTOR, KERNEL_TRUNCATION/IPAD
References
- ↑ S. Vijay, M. Schlipf, H. Miranda, F. Karsai, M. Kaltak, M. Marsman, and G. Kresse, Efficient periodic density functional theory calculations of charged molecules and surfaces using Coulomb kernel truncation, Phys. Rev. B 112, 045409 (2025).
- ↑ C. A. Rozzi, D. Varsano, A. Marini, E. K. Gross, A. J. Rubio, Phys. Rev. B 73, 20511 (2006).
- ↑ T. Sohier, M. Calandra, and F. Mauri, Phys. Rev. B 96, 75448 (2017).