Section ALMO_SCF

• Settings for a class of efficient linear scaling methods based on absolutely localized orbitals (ALMOs). ALMO methods are currently restricted to closed-shell molecular systems.

• Section path: CP2K_INPUT / FORCE_EVAL / DFT / ALMO_SCF

• This section cannot be repeated.

• This section cites the following reference: [Khaliullin2013]

• Subsections

  • ALMO_OPTIMIZER_DIIS
  • ALMO_OPTIMIZER_PCG
  • XALMO_OPTIMIZER_PCG

• Keywords

  • ALMO_ALGORITHM
  • ALMO_SCF_GUESS
  • DELOCALIZE_METHOD
  • EPS_FILTER
  • XALMO_R_CUTOFF_FACTOR

• Keyword descriptions

  ALMO_ALGORITHM
  	ALMO_ALGORITHM {Keyword}
  	Specifies the algorithm to update block-diagonal ALMOs during the SCF procedure.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: DIAG
  	List of valid keywords: DIAG DIIS-accelerated diagonalization controlled by ALMO_OPTIMIZER_DIIS. Recommended for large systems containing small fragments. PCG Energy minimization with a PCG algorithm controlled by ALMO_OPTIMIZER_PCG.

  ALMO_SCF_GUESS
  	ALMO_SCF_GUESS {Keyword}
  	The method to generate initial ALMOs.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: ATOMIC
  	List of valid keywords: ATOMIC Superpoisiton of atomic densities. MOLECULAR SCF calculations on single molecules controled by the regular SCF keywords outside ALMO options. This kind of calculation is expensive and only recommended if ALMO SCF does not converge from the ATOMIC guess.

  DELOCALIZE_METHOD
  	DELOCALIZE_METHOD {Keyword}
  	Methods to reintroduce electron delocalization, which is excluded with the block-diagonal ALMO reference. Electron delocalization can be computed using either fully delocalized MOs or spatially restricted ALMOs (called extended ALMOs or XALMOs). All methods below use a PCG optimizer controlled by XALMO_OPTIMIZER_PCG. The only exception is the non-iterative XALMO_1DIAG.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: XALMO_X
  	List of valid keywords: FULL_SCF Self-consistent treatment of delocalization without spatial restrictions FULL_X Single excitation correction (no Hamiltonian re-build) without spatial restrictions FULL_X_THEN_SCF Single excitation correction followed by full SCF procedure, both without spatial restrictions NONE Neglect electron delocalization XALMO_1DIAG Correction based on one diagonalization of the spatially projected Hamiltonian (XALMO) XALMO_SCF Self-consistent treatment of delocalization with spatial restrictions (XALMO) XALMO_X Single excitation correction (no Hamiltonian re-build) with spatial restrictions (XALMO)

  EPS_FILTER
  	EPS_FILTER {Real}
  	Threshold for the matrix sparsity filter
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-007

  XALMO_R_CUTOFF_FACTOR
  	XALMO_R_CUTOFF_FACTOR {Real}
  	Controls the localization radius of XALMOs: R_cutoff = XALMO_R_CUTOFF_FACTOR*(radius(at1)+radius(at2))
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.50000000E+000