Section RESPONSE_SOLVER

• Specifies the parameters of the linear scaling solver routines

• Section path: CP2K_INPUT / FORCE_EVAL / DFT / ENERGY_CORRECTION / RESPONSE_SOLVER

• This section cannot be repeated.

• This section cites the following reference: [VandeVondele2012]

• Subsections

  • none

• Keywords

  • EPS
  • EPS_FILTER
  • EPS_LANCZOS
  • MATRIX_CLUSTER_TYPE
  • MAX_ITER
  • MAX_ITER_LANCZOS
  • METHOD
  • PRECONDITIONER
  • RESTART
  • RESTART_EVERY
  • SINGLE_PRECISION_MATRICES
  • S_INVERSION
  • S_PRECONDITIONER
  • S_SQRT_METHOD
  • S_SQRT_ORDER

• Keyword descriptions

  EPS
  	EPS {Real}
  	Target accuracy for the convergence of the conjugate gradient.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-012

  EPS_FILTER
  	EPS_FILTER {Real}
  	Threshold used for filtering matrix operations.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-010

  EPS_LANCZOS
  	EPS_LANCZOS {Real}
  	Threshold used for lanczos estimates.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-003

  MATRIX_CLUSTER_TYPE
  	MATRIX_CLUSTER_TYPE {Keyword}
  	Specify how atomic blocks should be clustered in the used matrices, in order to improve flop rate, and possibly speedup the matrix multiply. Note that the atomic s_preconditioner can not be used.Furthermore, since screening is on matrix blocks, slightly more accurate results can be expected with molecular.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: ATOMIC
  	List of valid keywords: ATOMIC Using atomic blocks MOLECULAR Using molecular blocks.

  MAX_ITER
  	MAX_ITER {Integer}
  	Maximum number of conjugate gradient iterationto be performed for one optimization.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 50

  MAX_ITER_LANCZOS
  	MAX_ITER_LANCZOS {Integer}
  	Maximum number of lanczos iterations.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 128

  METHOD
  	METHOD {Keyword}
  	Algorithm used to solve response equation.Both solver are conjugate gradient based, but use either a vector (MO-coefficient)or density matrix formalism in the orthonormal AO-basis to obtain response density
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: AO_ORTHO
  	List of valid keywords: AO_ORTHO Solver based on density matrix formalism MO_SOLVER Solver based on MO (vector) formalism

  PRECONDITIONER
  	PRECONDITIONER {Keyword}
  	Type of preconditioner to be used with MO conjugate gradient solver. They differ in effectiveness, cost of construction, cost of application. Properly preconditioned minimization can be orders of magnitude faster than doing nothing.Only multi-level conjugate gradient preconditioner (MULTI_LEVEL) available for AO response solver (AO_ORTHO).
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: MULTI_LEVEL
  	List of valid keywords: FULL_ALL Most effective state selective preconditioner based on diagonalization, requires the ENERGY_GAP parameter to be an underestimate of the HOMO-LUMO gap. This preconditioner is recommended for almost all systems, except very large systems where make_preconditioner would dominate the total computational cost. FULL_KINETIC Cholesky inversion of S and T, fast construction, robust, and relatively good, use for very large systems. FULL_SINGLE Based on H-eS diagonalisation, not as good as FULL_ALL, but somewhat cheaper to apply. FULL_SINGLE_INVERSE Based on H-eS cholesky inversion, similar to FULL_SINGLE in preconditioning efficiency but cheaper to construct, might be somewhat less robust. Recommended for large systems. FULL_S_INVERSE Cholesky inversion of S, not as good as FULL_KINETIC, yet equally expensive. MULTI_LEVEL Based on same CG as AO-solver itself, but uses cheaper linear transformation NONE skip preconditioning

  RESTART
  	RESTART {Logical}
  	Restart the response calculation if the restart file exists
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  RESTART_EVERY
  	RESTART_EVERY {Integer}
  	Restart the conjugate gradient after the specified number of iterations.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 50

  SINGLE_PRECISION_MATRICES
  	SINGLE_PRECISION_MATRICES {Logical}
  	Matrices used within the LS code can be either double or single precision.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  S_INVERSION
  	S_INVERSION {Keyword}
  	Method used to compute the inverse of S.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: SIGN_SQRT
  	List of valid keywords: HOTELLING Using the Hotellign iteration. SIGN_SQRT Using the inverse sqrt as obtained from sign function iterations.

  S_PRECONDITIONER
  	S_PRECONDITIONER {Keyword}
  	Preconditions S with some appropriate form.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: ATOMIC
  	List of valid keywords: ATOMIC Using atomic blocks MOLECULAR Using molecular sub-blocks. Recommended if molecules are defined and not too large. NONE No preconditioner

  S_SQRT_METHOD
  	S_SQRT_METHOD {Keyword}
  	Method for the caclulation of the sqrt of S.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: NEWTONSCHULZ
  	List of valid keywords: NEWTONSCHULZ Using a Newton-Schulz-like iteration PROOT Using the p-th root method.

  S_SQRT_ORDER
  	S_SQRT_ORDER {Integer}
  	Order of the iteration method for the calculation of the sqrt of S.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 3
  	Alias names for this keyword: SIGN_SQRT_ORDER