KERNEL_TRUNCATION/LTRUNCATE

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]. 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 that is of the same extend as the computational cell in each direction. This implies increasing the FFT-grid sizes by a certain factor (see KERNEL_TRUNCATION/IPAD) and thus leads to a significant increase in computational cost.

Tip: Use the KERNEL_TRUNCATION/LCOARSEN = T to avoid the increased FFT-grid sizes.

Mind:

KERNEL_TRUNCATION/LTRUNCATE acts as a "super-tag", i.e. unless this tag is switched on further options in KERNEL_TRUNCATION will be ignored.
This tag is only available as of VASP.6.5.0.

Detailed information about the setting are documented on respective related tags.

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).

[vijay:prb:2025-1] 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).

[1]

Related tags and articles

References