Section DIIS

• Activate the DIIS based optimization procedure for BAND

• Section path: CP2K_INPUT / MOTION / BAND / OPTIMIZE_BAND / DIIS

• This section cannot be repeated and cannot be optional.

• Subsections

  • none

• Keywords

  • CHECK_DIIS
  • MAX_SD_STEPS
  • MAX_STEPS
  • MAX_STEPSIZE
  • NO_LS
  • NP_LS
  • N_DIIS
  • STEPSIZE

• Keyword descriptions

  CHECK_DIIS
  	Performes a series of checks on the DIIS solution in order to accept the DIIS step. If set to .FALSE. the only check performed is that the angle between the DIIS solution and the reference vector is less than Pi/2. Can be useful if many DIIS steps are rejected.
  	This optional keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.

  MAX_SD_STEPS
  	Specify the maximum number of SD steps to perform before switching on DIIS (the minimum number will always be equal to N_DIIS).
  	This optional keyword cannot be repeated and it expects precisely one integer.
  	Default value: 1

  MAX_STEPS
  	Specify the maximum number of optimization steps
  	This optional keyword cannot be repeated and it expects precisely one integer.
  	Default value: 100

  MAX_STEPSIZE
  	MAX_STEPSIZE <REAL>
  	Maximum stepsize used for the line search, sometimes this parametercan be reduced to stablize the LS for particularly difficult initial geometries
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 2.00000000E+00

  NO_LS
  	Does not perform LS during SD. Useful in combination with a proper STEPSIZE for particularly out of equilibrium starting geometries.
  	This optional keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  NP_LS
  	NP_LS <INTEGER>
  	Number of points used in the line search SD.
  	This optional keyword cannot be repeated and it expects precisely one integer.
  	Default value: 2

  N_DIIS
  	N_DIIS 4
  	Number of history vectors to be used with DIIS
  	This optional keyword cannot be repeated and it expects precisely one integer.
  	Default value: 7
  	Alias names for this keyword: NDIIS

  STEPSIZE
  	STEPSIZE <REAL>
  	Initial stepsize used for the line search, sometimes this parametercan be reduced to stablize DIIS
  	This optional keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E+00