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 references: [Khaliullin2013] [Scheiber2018]

• Subsections

  • ALMO_OPTIMIZER_DIIS
  • ALMO_OPTIMIZER_PCG
  • ALMO_OPTIMIZER_TRUSTR
  • ANALYSIS
  • MATRIX_ITERATE
  • NLMO_OPTIMIZER_PCG
  • XALMO_OPTIMIZER_PCG
  • XALMO_OPTIMIZER_TRUSTR

• Keywords

  • ALMO_ALGORITHM
  • ALMO_EXTRAPOLATION_ORDER
  • ALMO_SCF_GUESS
  • CONSTRUCT_NLMOS
  • DELOCALIZE_METHOD
  • EPS_FILTER
  • MO_OVERLAP_INV_ALG
  • RETURN_ORTHOGONALIZED_MOS
  • XALMO_ALGORITHM
  • XALMO_EXTRAPOLATION_ORDER
  • XALMO_R_CUTOFF_FACTOR
  • XALMO_TRIAL_WF

• 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. SKIP Skip optimization of block-diagonal ALMOs. TRUST_REGION Trust-region optimizer is recommended if PCG has difficulty converging. It is controlled by ALMO_OPTIMIZER_TRUSTR

  ALMO_EXTRAPOLATION_ORDER
  	ALMO_EXTRAPOLATION_ORDER {Integer}
  	Number of previous states used for the ASPC extrapolation of the ALMO initial guess. 0 implies that the guess is given by ALMO_SCF_GUESS at each step.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 3

  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 Superposition of atomic densities. MOLECULAR SCF calculations on single molecules controlled 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.

  CONSTRUCT_NLMOS
  	CONSTRUCT_NLMOS {Logical}
  	Turns on post-SCF construction of NLMOs
  	This keyword cannot be repeated and it expects precisely one logical.
  	Default value: .FALSE.

  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 either a PCG or trust-regionoptimizers controlled by XALMO_OPTIMIZER_* subsections. 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

  MO_OVERLAP_INV_ALG
  	MO_OVERLAP_INV_ALG {Keyword}
  	Algorithm to invert MO overlap matrix.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: LS_HOTELLING
  	List of valid keywords: DENSE_CHOLESKY Stable but dense Cholesky algorithm. Cubically scaling. LS_HOTELLING Linear scaling iterative Hotelling algorithm. Fast for large sparse matrices. LS_TAYLOR Linear scaling algorithm based on Taylor expansion of (A+B)^(-1).

  RETURN_ORTHOGONALIZED_MOS
  	RETURN_ORTHOGONALIZED_MOS {Logical}
  	Orthogonalize final ALMOs before they are returnedto Quickstep (i.e. for calculation of properties)
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.

  XALMO_ALGORITHM
  	XALMO_ALGORITHM {Keyword}
  	Specifies the algorithm to update ALMOs on eXtended domains (XALMOs).
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: PCG
  	List of valid keywords: DIAG DIIS-accelerated diagonalization. PCG PCG algorithm controlled by XALMO_OPTIMIZER_PCG. TRUST_REGION Trust-region optimizer controlled by XALMO_OPTIMIZER_TRUSTR

  XALMO_EXTRAPOLATION_ORDER
  	XALMO_EXTRAPOLATION_ORDER {Integer}
  	Number of previous states used for the ASPC extrapolation of the initial guess for the delocalization correction.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 0

  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

  XALMO_TRIAL_WF
  	XALMO_TRIAL_WF {Keyword}
  	Determines the form of the trial XALMOs.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: PROJECT_R0_OUT
  	List of valid keywords: PROJECT_R0_OUT Block-diagonal ALMOs plus the XALMO term projected onto the unoccupied ALMO-subspace. SIMPLE Straightforward AO-basis expansion.