Section CANONICAL_GRADIENTS

• Parameters influencing gradient calculations of canonical RI methods. Ignored if the IM_TIME section is set.

• Section path: CP2K_INPUT / FORCE_EVAL / DFT / XC / WF_CORRELATION / CANONICAL_GRADIENTS

• This section cannot be repeated.

• Subsections

  • CPHF

• Keywords

  • DOT_PRODUCT_BLKSIZE
  • EPS_CANONICAL
  • FREE_HFX_BUFFER
  • MAX_PARALLEL_COMM
  • USE_OLD_GRADIENT_CODE

• Keyword descriptions

  DOT_PRODUCT_BLKSIZE
  	DOT_PRODUCT_BLKSIZE {Integer}
  	Dot products for the calculation of the RPA/SOS-MP2 density matrices are calculated in batches of the size given by this keyword. Larger block sizes improve the performance but reduce the numerical accuracy. Recommended block sizes are multiples of the number of doubles per cache line (usually 8). Ignored with MP2 gradients. Set it to -1 to prevent blocking.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: -1

  EPS_CANONICAL
  	EPS_CANONICAL {Real}
  	Threshold under which a given ij or ab pair is considered to be degenerate and its contribution to the density matrix is calculated directly. Ignored in case of energy-only calculation.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-007

  FREE_HFX_BUFFER
  	FREE_HFX_BUFFER {Logical}
  	Free the buffer containing the 4 center integrals used in the Hartree-Fock exchange calculation. This will be effective only for gradients calculations, since for the energy only case, the buffers are released by default. (Right now debugging only).
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.

  MAX_PARALLEL_COMM
  	MAX_PARALLEL_COMM {Integer}
  	Sets the maximum number of parallel communication steps of the non-blocking communication scheme. The number of channels is determined from the available memory. If set to a value smaller than one, CP2K will use all memory for communication. A value of one enforces the blocking communication scheme increasing the communication costs.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 2

  USE_OLD_GRADIENT_CODE
  	USE_OLD_GRADIENT_CODE {Logical}
  	Use the original RI-MP2 gradient code.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.