Section CELL_REF

• Input parameters needed to set up the reference cell. This option can be used to keep the FFT grid fixed while running a cell optimization or NpT molecular dynamics.

• Section path: CP2K_INPUT / FORCE_EVAL / SUBSYS / CELL / CELL_REF

• This section cannot be repeated.

• Subsections

  • none

• Keywords

  • A
  • ABC
  • ALPHA_BETA_GAMMA
  • B
  • C
  • CELL_FILE_FORMAT
  • CELL_FILE_NAME
  • MULTIPLE_UNIT_CELL
  • PERIODIC
  • SYMMETRY

• Keyword descriptions

  A
  	A {Real} {Real} {Real}
  	Specify the Cartesian components for the cell vector A. This defines the first column of the h matrix.
  	This keyword cannot be repeated and it expects precisely 3 reals.
  	Default unit: [angstrom]

  ABC
  	ABC {Real} {Real} {Real}
  	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.
  	This keyword cannot be repeated and it expects precisely 3 reals.
  	Default unit: [angstrom]

  ALPHA_BETA_GAMMA
  	ALPHA_BETA_GAMMA {Real} {Real} {Real}
  	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.
  	This keyword cannot be repeated and it expects precisely 3 reals.
  	Default values: 9.00000000E+001 9.00000000E+001 9.00000000E+001
  	Default unit: [deg]
  	Alias names for this keyword: ANGLES

  B
  	B {Real} {Real} {Real}
  	Specify the Cartesian components for the cell vector B. This defines the second column of the h matrix.
  	This keyword cannot be repeated and it expects precisely 3 reals.
  	Default unit: [angstrom]

  C
  	C {Real} {Real} {Real}
  	Specify the Cartesian components for the cell vector C. This defines the third column of the h matrix.
  	This keyword cannot be repeated and it expects precisely 3 reals.
  	Default unit: [angstrom]

  CELL_FILE_FORMAT
  	CELL_FILE_FORMAT {Keyword}
  	Specify the format of the cell file (if used)
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: CP2K
  	List of valid keywords: CIF Cell info from CIF file. CP2K Cell info in the CP2K native format. XSC Cell info in the XSC format (NAMD)

  CELL_FILE_NAME
  	CELL_FILE_NAME {String}
  	Possibility to read the cell from an external file
  	This keyword cannot be repeated and it expects precisely one string.

  MULTIPLE_UNIT_CELL
  	MULTIPLE_UNIT_CELL {Integer} {Integer} {Integer}
  	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.
  	This keyword cannot be repeated and it expects precisely 3 integers.
  	Default values: 1 1 1

  PERIODIC
  	PERIODIC {Keyword}
  	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.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: XYZ
  	List of valid keywords: NONE Without description, yet. X Without description, yet. XY Without description, yet. XYZ Without description, yet. XZ Without description, yet. Y Without description, yet. YZ Without description, yet. Z Without description, yet.

  SYMMETRY
  	SYMMETRY {Keyword}
  	Imposes an initial cell symmetry.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: NONE
  	List of valid keywords: CUBIC Cubic (a = b = c, α = β = γ = 90°) HEXAGONAL Hexagonal (a = b ≠ c, α = β = 90°, γ = 60°) MONOCLINIC Monoclinic (a ≠ b ≠ c ≠ a, α = γ = 90°, β ≠ 90°) MONOCLINIC_GAMMA_AB Monoclinic (a = b ≠ c, α = β = 90°, γ ≠ 90°) NONE No cell symmetry ORTHORHOMBIC Orthorhombic (a ≠ b ≠ c, α = β = γ = 90°) RHOMBOHEDRAL Rhombohedral (a = b = c, α = β = γ ≠ 90°) TETRAGONAL Tetragonal (alias for TETRAGONAL_AB) 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°) TRICLINIC Triclinic (a ≠ b ≠ c ≠ a, α ≠ β ≠ γ ≠ α ≠ 90°)