Section MOM

• Define type and parameters for the maximum overlap method (MOM) to determine orbital occupancies. The MOM procedures activated by this section are only active for diagonalization methods, i.e. not with minimization methods based on OT. Incompatible with core-level excitation spectra (XAS).

• Section path: CP2K_INPUT / FORCE_EVAL / DFT / XAS / SCF / MOM

• This section cannot be repeated.

• This section cites the following references: [Barca2018] [Gilbert2008]

• Subsections

  • none

• Keywords

  • SECTION_PARAMETERS
  • DEOCC_ALPHA
  • DEOCC_BETA
  • MOM_TYPE
  • OCC_ALPHA
  • OCC_BETA
  • PROJ_FORMULA
  • START_ITER

• Keyword descriptions

  SECTION_PARAMETERS
  	&MOM {Logical}
  	Controls the activation of the MOM procedure
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  DEOCC_ALPHA
  	DEOCC_ALPHA {Integer} ...
  	Alpha orbitals to be deoccupied
  	This keyword cannot be repeated and it expects a list of integers.
  	Default value: 0

  DEOCC_BETA
  	DEOCC_BETA {Integer} ...
  	Beta orbitals to be deoccupied
  	This keyword cannot be repeated and it expects a list of integers.
  	Default value: 0

  MOM_TYPE
  	MOM_TYPE {Keyword}
  	Revision of the maximum overlap method to be used
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: MOM
  	List of valid keywords: IMOM Initial-MOM which uses molecular orbitals of the initial guess as reference MOM Originally proposed MOM protocol which uses molecular orbitals from the previous SCF cycle as reference

  OCC_ALPHA
  	OCC_ALPHA {Integer} ...
  	Alpha orbitals to be occupied
  	This keyword cannot be repeated and it expects a list of integers.
  	Default value: 0

  OCC_BETA
  	OCC_BETA {Integer} ...
  	Beta orbitals to be occupied
  	This keyword cannot be repeated and it expects a list of integers.
  	Default value: 0

  PROJ_FORMULA
  	PROJ_FORMULA {Keyword}
  	Projection formula to be used
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: NORM
  	List of valid keywords: NORM The one which ignores the phase of molecular orbitals: proj_j = \sqrt(\sum_i overlap(i, j)^2) SUM The one proposed in the original paper: proj_j = |\sum_i overlap(i, j)|

  START_ITER
  	START_ITER {Integer}
  	SCF iteration cycle to start the MOM procedure. Could be used for ground state calculations only in order to stabilise oscillating SCF iterations
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 0