POISSON

Controls the Poisson solver and electrostatic boundary conditions used by DFT. [Edit on GitHub]

Subsections

Keywords

Keyword descriptions

PERIODIC

Type: enum
Default: XYZ
Usage: PERIODIC (x|y|z|xy|xz|yz|xyz|none)

Description: Specifies the directions in which periodic boundary conditions apply to electrostatics. See the CELL section for the periodicity used by geometry and pair lists; the settings are usually the same.

Valid values:

  • X

  • Y

  • Z

  • XY

  • XZ

  • YZ

  • XYZ

  • NONE

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POISSON_SOLVER

Type: enum
Default: PERIODIC
Aliases: POISSON, PSOLVER
Usage: POISSON_SOLVER char

Description: Specify which kind of solver to use to solve the Poisson equation.

Valid values:

  • PERIODIC PERIODIC is only available for fully (3D) periodic systems.

  • ANALYTIC ANALYTIC is available for 0D, 1D and 2D periodic solutions using analytical green functions in the g space (slow convergence).

  • MT MT (Martyna Tuckermann) decoupling that interacts only with the nearest neighbor. Beware results are completely wrong if the cell is smaller than twice the cluster size (with electronic density). Available for 0D and 2D systems.

  • MULTIPOLE MULTIPOLE uses a scheme that fits the total charge with one gaussian per atom. Available only for cluster (0D) systems.

  • WAVELET WAVELET allows for 0D, 2D and 3D systems. For 2D systems all PERIODIC XY, XZ and YZ combinations are accepted. It does not require very large unit cells, only that the density goes to zero on the faces of the cell. The use of PREFERRED_FFT_LIBRARY FFTSG is required.

  • IMPLICIT IMPLICIT allows for 0D, 1D, 2D and 3D systems.

References: Blöchl1995, Martyna1999, Genovese2006, Genovese2007

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