Section FIXED_ATOMS

• This section is used to constraint the fractional atomic position (X,Y,Z). Note that fractional coordinates are constrained, not real space coordinates. In case a restraint is specified the value of the TARGET is considered to be the value of the coordinates at the beginning of the run or alternatively the corresponding value in the section: FIX_ATOM_RESTART.

• Section path: CP2K_INPUT / MOTION / CONSTRAINT / FIXED_ATOMS

• This section can be repeated.

• Subsections

  • RESTRAINT

• Keywords

  • COMPONENTS_TO_FIX
  • EXCLUDE_MM
  • EXCLUDE_QM
  • LIST
  • MM_SUBSYS
  • MOLNAME
  • QM_SUBSYS

• Keyword descriptions

  COMPONENTS_TO_FIX
  	COMPONENTS_TO_FIX {Keyword}
  	Specify which fractional components (X,Y,Z or combinations) of the atoms specified in the section will be constrained/restrained.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: XYZ
  	List of valid keywords: X Fix only X component XY Fix X-Y components XYZ Fix the full components of the atomic position. XZ Fix X-Z components Y Fix only Y component YZ Fix Y-Z components Z Fix only Z component

  EXCLUDE_MM
  	EXCLUDE_MM {Logical}
  	Does not apply the constraint to the MM region within a QM/MM calculation. This keyword is active only together with MOLNAME
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  EXCLUDE_QM
  	EXCLUDE_QM {Logical}
  	Does not apply the constraint to the QM region within a QM/MM calculation. This keyword is active only together with MOLNAME
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  LIST
  	LIST {Integer} ... or a range {Integer}..{Integer}
  	Specifies a list of atoms to freeze.
  	This keyword can be repeated and it expects a list of integers.

  MM_SUBSYS
  	MM_SUBSYS {Keyword}
  	In a QM/MM run all MM atoms are fixed according to the argument.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: NONE
  	List of valid keywords: ATOMIC only the MM atoms itself MOLECULAR the full molecule/residue that contains a MM atom (i.e. some QM atoms might be fixed as well) NONE fix nothing
  	Alias names for this keyword: PROTEIN

  MOLNAME
  	MOLNAME {Word} ...
  	Specifies the name of the molecule to fix
  	This keyword can be repeated and it expects a list of words.
  	Alias names for this keyword: SEGNAME

  QM_SUBSYS
  	QM_SUBSYS {Keyword}
  	In a QM/MM run all QM atoms are fixed according to the argument.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: NONE
  	List of valid keywords: ATOMIC only the QM atoms itself MOLECULAR the full molecule/residue that contains a QM atom (i.e. some MM atoms might be fixed as well) NONE fix nothing