# 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

## 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

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 = XYZ

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]