Section LBFGS

• Provides parameters to tune the limited memory BFGS (LBFGS) optimization

• Section path: CP2K_INPUT / MOTION / CELL_OPT / LBFGS

• This section cannot be repeated and can be optional.

• This section cites the following reference: [BYRD1995]

• Subsections

  • none

• Keywords

  • MAX_F_PER_ITER
  • MAX_H_RANK
  • WANTED_PROJ_GRADIENT
  • WANTED_REL_F_ERROR

• Keyword descriptions

  MAX_F_PER_ITER
  	MAX_F_PER_ITER {INTEGER}
  	Maximum number of force evaluations per iteration(used for the line search)
  	This optional keyword cannot be repeated and it expects precisely one integer.
  	Default value: 3

  MAX_H_RANK
  	MAX_H_RANK {INTEGER}
  	Maximum rank (and consequently size) of the approximate Hessian matrix used by the LBFGS optimizer. Larger values (e.g. 30) will accelerate the convergence behaviour at the cost of a larger memory consumption.
  	This optional keyword cannot be repeated and it expects precisely one integer.
  	Default value: 5

  WANTED_PROJ_GRADIENT
  	WANTED_PROJ_GRADIENT {REAL}
  	Convergence criterium (overrides the general ones):Requested norm threshold of the gradient multiplied by the approximate Hessian.
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-16
  	Default unit: [internal_cp2k]

  WANTED_REL_F_ERROR
  	WANTED_REL_F_ERROR {REAL}
  	Convergence criterium (overrides the general ones):Requested relative error on the objective functionof the optimizer (the energy)
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-16
  	Default unit: [internal_cp2k]