Section SHELL

• This section specifies the parameters for shell-model potentials

• Section path: CP2K_INPUT / FORCE_EVAL / MM / FORCEFIELD / SHELL

• This section can be repeated and cannot be optional.

• Subsections

  • none

• Keywords

  • SECTION_PARAMETERS
  • CORE_CHARGE
  • K2_SPRING
  • K4_SPRING
  • MASS_FRACTION
  • MAX_DISTANCE
  • SHELL_CHARGE
  • SHELL_CUTOFF

• Keyword descriptions

  SECTION_PARAMETERS
  	H
  	The kind for which the shell potential parameters are given
  	This optional keyword cannot be repeated and it expects precisely one word.
  	Default value: DEFAULT

  CORE_CHARGE
  	CORE_CHARGE {REAL}
  	Partial charge assigned to the core (electron charge units)
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 0.00000000E+00
  	Alias names for this keyword: CORE

  K2_SPRING
  	K2_SPRING {REAL}
  	Force constant k2 of the spring potential 1/2*k2*r^2 + 1/24*k4*r^4 binding a core-shell pair when a core-shell potential is employed.
  	This required keyword cannot be repeated and it expects precisely one real.
  	Default value: -1.00000000E+00
  	Default unit: [bohr^-2hartree]
  	Alias names for this keyword: K2, SPRING

  K4_SPRING
  	K4_SPRING {REAL}
  	Force constant k4 of the spring potential 1/2*k2*r^2 + 1/24*k4*r^4 binding a core-shell pair when a core-shell potential is employed. By default a harmonic spring potential is used, i.e. k4 is zero.
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 0.00000000E+00
  	Default unit: [bohr^-4hartree]
  	Alias names for this keyword: K4

  MASS_FRACTION
  	MASS_FRACTION {REAL}
  	Fraction of the mass of the atom to be assigned to the shell
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-01
  	Alias names for this keyword: MASS

  MAX_DISTANCE
  	MAX_DISTANCE 0.0
  	Assign a maximum elongation of the spring, if negative no limit is imposed
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: -5.29177209E-01
  	Default unit: [angstrom]

  SHELL_CHARGE
  	SHELL_CHARGE {REAL}
  	Partial charge assigned to the shell (electron charge units)
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 0.00000000E+00
  	Alias names for this keyword: SHELL

  SHELL_CUTOFF
  	SHELL_CUTOFF -1.0
  	Define a screening function to exclude some neighbors of the shell when electrostatic interaction are considered, if negative no screening is operated
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: -5.29177209E-01
  	Default unit: [angstrom]