Section EXTERNAL_POTENTIAL

• Section controlling the presence of an electrostatic external potential dependent on the atomic positions (X,Y,Z). As the external potential is currently applied via a grid, it only works with DFT based methods (GPW/GAPW) that already use a grid based approach to solve the Poisson equation.

• Section path: CP2K_INPUT / FORCE_EVAL / DFT / EXTERNAL_POTENTIAL

• This section cannot be repeated.

• Subsections

  • none

• Keywords

  • DX
  • ERROR_LIMIT
  • FUNCTION
  • PARAMETERS
  • READ_FROM_CUBE
  • SCALING_FACTOR
  • STATIC
  • UNITS
  • VALUES

• Keyword descriptions

  DX
  	DX {Real}
  	Parameter used for computing the derivative with the Ridders' method.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-001
  	Default unit: [bohr]

  ERROR_LIMIT
  	ERROR_LIMIT {Real}
  	Checks that the error in computing the derivative is not larger than the value set; in case error is larger a warning message is printed.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-012

  FUNCTION
  	FUNCTION {String}
  	Specifies the functional form in mathematical notation. Variables must be the atomic coordinates (X,Y,Z) of the grid.
  	This keyword cannot be repeated and it expects precisely one string.

  PARAMETERS
  	PARAMETERS {Word} ...
  	Defines the parameters of the functional form
  	This keyword can be repeated and it expects a list of words.

  READ_FROM_CUBE
  	READ_FROM_CUBE {Logical}
  	Switch for reading the external potential from file pot.cube. The values of the potential must be on the grid points of the realspace grid.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  SCALING_FACTOR
  	SCALING_FACTOR {Real}
  	A factor for scaling the the external potential that is read from file.The value of the potential at each grid point is multiplied by this factor.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E+000

  STATIC
  	STATIC {Logical}
  	Specifies the external potential as STATIC or time dependent. At the moment only static potentials are implemented.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.

  UNITS
  	UNITS {Word} ...
  	Optionally, allows to define valid CP2K unit strings for each parameter value. It is assumed that the corresponding parameter value is specified in this unit.
  	This keyword can be repeated and it expects a list of words.

  VALUES
  	VALUES {Real} ...
  	Defines the values of parameter of the functional form
  	This keyword can be repeated and it expects a list of reals.
  	Default unit: [internal_cp2k]