Section XALMO_OPTIMIZER_PCG

• Controls the PCG optimization of extended ALMOs.

• Section path: CP2K_INPUT / FORCE_EVAL / DFT / ALMO_SCF / XALMO_OPTIMIZER_PCG

• This section cannot be repeated.

• Subsections

  • XALMO_NEWTON_PCG_SOLVER

• Keywords

  • CONJUGATOR
  • EPS_ERROR
  • EPS_ERROR_EARLY
  • LIN_SEARCH_EPS_ERROR
  • LIN_SEARCH_STEP_SIZE_GUESS
  • MAX_ITER
  • MAX_ITER_EARLY
  • MAX_ITER_OUTER_LOOP
  • PRECONDITIONER
  • PRECOND_FILTER_THRESHOLD

• Keyword descriptions

  CONJUGATOR
  	CONJUGATOR {Keyword}
  	Various methods to compute step directions in the PCG optimization
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: HAGER_ZHANG
  	List of valid keywords: DAI_YUAN Dai and Yuan FLETCHER Fletcher (Conjugate descent) FLETCHER_REEVES Fletcher and Reeves HAGER_ZHANG Hager and Zhang HESTENES_STIEFEL Hestenes and Stiefel LIU_STOREY Liu and Storey POLAK_RIBIERE Polak and Ribiere ZERO Steepest descent

  EPS_ERROR
  	EPS_ERROR {Real}
  	Target value of the MAX norm of the error
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-005

  EPS_ERROR_EARLY
  	EPS_ERROR_EARLY {Real}
  	Target value of the MAX norm of the error for truncated SCF (e.g. Langevin-corrected MD). Negative values mean that this keyword is not used.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: -1.00000000E+000

  LIN_SEARCH_EPS_ERROR
  	LIN_SEARCH_EPS_ERROR {Real}
  	Target value of the gradient norm during the linear search
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-003

  LIN_SEARCH_STEP_SIZE_GUESS
  	LIN_SEARCH_STEP_SIZE_GUESS {Real}
  	The size of the first step in the linear search
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E+000

  MAX_ITER
  	MAX_ITER {Integer}
  	Maximum number of iterations
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 20

  MAX_ITER_EARLY
  	MAX_ITER_EARLY {Integer}
  	Maximum number of iterations for truncated SCF (e.g. Langevin-corrected MD). Negative values mean that this keyword is not used.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: -1

  MAX_ITER_OUTER_LOOP
  	MAX_ITER_OUTER_LOOP {Integer}
  	Maximum number of iterations in the outer loop. Use the outer loop to update the preconditioner and reset the conjugator. This can speed up convergence significantly.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 0

  PRECONDITIONER
  	PRECONDITIONER {Keyword}
  	Select a preconditioner for the conjugate gradient optimization
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: DEFAULT
  	List of valid keywords: DEFAULT Same as DOMAIN preconditioner DOMAIN Invert preconditioner domain-by-domain. The main component of the linear scaling algorithm FULL Solve linear equations step=-H.grad on the entire space NONE Do not use preconditioner

  PRECOND_FILTER_THRESHOLD
  	PRECOND_FILTER_THRESHOLD {Real}
  	Select eigenvalues of the preconditioner that are smaller than the threshold and project out the corresponding eigenvectors from the gradient. No matter how large the threshold is the maximum number of projected eienvectors for a fragment equals to the number of occupied orbitals of fragment's neighbors.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 5.00000000E-001