# CELL

Input parameters needed to set up the simulation cell. Simple products and fractions combined with functions of a single number can be used like 2/3, 0.3*COS(60) or -SQRT(3)/2. The functions COS, EXP, LOG, LOG10, SIN, SQRT, and TAN are available. [Edit on GitHub]

Subsections

- CELL_REF

## Keywords

- A

- ABC

- ALPHA_BETA_GAMMA

- B

- C

- CELL_FILE_FORMAT

- CELL_FILE_NAME

- MULTIPLE_UNIT_CELL

- PERIODIC

- SYMMETRY

## Keyword descriptions

A: real[3] = [angstrom]

  Usage: A 10.000 0.000 0.000

  Specify the Cartesian components for the cell vector A. This defines the first column of the h matrix. [Edit on GitHub]

ABC: real[3] = [angstrom]

  Usage: ABC 10.000 10.000 10.000

  Specify the lengths of the cell vectors A, B, and C, which defines the diagonal elements of h matrix for an orthorhombic cell. For non-orthorhombic cells it is possible either to specify the angles ALPHA, BETA, GAMMA via ALPHA_BETA_GAMMA keyword or alternatively use the keywords A, B, and C. The convention is that A lies along the X-axis, B is in the XY plane. [Edit on GitHub]

ALPHA_BETA_GAMMA: real[3] = 9.00000000E+001 9.00000000E+001 9.00000000E+001 [deg]

  Aliases: ANGLES

  Usage: ALPHA_BETA_GAMMA [deg] 90.0 90.0 120.0

  Specify the angles between the vectors A, B and C when using the ABC keyword. The convention is that A lies along the X-axis, B is in the XY plane. ALPHA is the angle between B and C, BETA is the angle between A and C and GAMMA the angle between A and B. [Edit on GitHub]

B: real[3] = [angstrom]

  Usage: B 0.000 10.000 0.000

  Specify the Cartesian components for the cell vector B. This defines the second column of the h matrix. [Edit on GitHub]

C: real[3] = [angstrom]

  Usage: C 0.000 0.000 10.000

  Specify the Cartesian components for the cell vector C. This defines the third column of the h matrix. [Edit on GitHub]

CELL_FILE_FORMAT: enum = CP2K

  Usage: CELL_FILE_FORMAT (CP2K|CIF|XSC)

  Valid values:

  - `CP2K` Cell info in the CP2K native format.

  - `CIF` Cell info from CIF file.

  - `XSC` Cell info in the XSC format (NAMD)

  Specify the format of the cell file (if used) [Edit on GitHub]

CELL_FILE_NAME: string

  Usage: CELL_FILE_NAME <CHARACTER>

  Possibility to read the cell from an external file [Edit on GitHub]

MULTIPLE_UNIT_CELL: integer[3] = 1 1 1

  Usage: MULTIPLE_UNIT_CELL 1 1 1

  Specifies the numbers of repetition in space (X, Y, Z) of the defined cell, assuming it as a unit cell. This keyword affects only the CELL specification. The same keyword in SUBSYS%TOPOLOGY%MULTIPLE_UNIT_CELL should be modified in order to affect the coordinates specification. [Edit on GitHub]

PERIODIC: enum = NONE

  Usage: PERIODIC (x|y|z|xy|xz|yz|xyz|none)

  Valid values:

  - `X`

  - `Y`

  - `Z`

  - `XY`

  - `XZ`

  - `YZ`

  - `XYZ`

  - `NONE`

  Specify the directions for which periodic boundary conditions (PBC) will be applied. Important notice: This applies to the generation of the pair lists as well as to the application of the PBCs to positions. See the POISSON section to specify the periodicity used for the electrostatics. Typically the settings should be the same. [Edit on GitHub]

SYMMETRY: enum = NONE

  Usage: SYMMETRY monoclinic

  Valid values:

  - `NONE` No cell symmetry

  - `TRICLINIC` Triclinic (a ≠ b ≠ c ≠ a, α ≠ β ≠ γ ≠ α ≠ 90°)

  - `MONOCLINIC` Monoclinic (a ≠ b ≠ c, α = γ = 90°, β ≠ 90°)

  - `MONOCLINIC_GAMMA_AB` Monoclinic (a = b ≠ c, α = β = 90°, γ ≠ 90°)

  - `ORTHORHOMBIC` Orthorhombic (a ≠ b ≠ c, α = β = γ = 90°)

  - `TETRAGONAL_AB` Tetragonal (a = b ≠ c, α = β = γ = 90°)

  - `TETRAGONAL_AC` Tetragonal (a = c ≠ b, α = β = γ = 90°)

  - `TETRAGONAL_BC` Tetragonal (a ≠ b = c, α = β = γ = 90°)

  - `TETRAGONAL` Tetragonal (alias for TETRAGONAL_AB)

  - `RHOMBOHEDRAL` Rhombohedral (a = b = c, α = β = γ ≠ 90°)

  - `HEXAGONAL` Hexagonal (alias for HEXAGONAL_GAMMA_60)

  - `HEXAGONAL_GAMMA_60` Hexagonal (a = b ≠ c, α = β = 90°, γ = 60°)

  - `HEXAGONAL_GAMMA_120` Hexagonal (a = b ≠ c, α = β = 90°, γ = 120°)

  - `CUBIC` Cubic (a = b = c, α = β = γ = 90°)

  Imposes an initial cell symmetry. [Edit on GitHub]