Section LOW_SCALING

• Cubic scaling RI-RPA, GW and Laplace-SOS-MP2 method using the imaginary time formalism. EPS_GRID in WFC_GPW section controls accuracy / req. memory for 3-center integrals. SORT_BASIS EXP should be specified in DFT section.  [Edit on GitHub]

• Section path: CP2K_INPUT / FORCE_EVAL / PROPERTIES / TDDFPT / XC / WF_CORRELATION / LOW_SCALING

• This section cannot be repeated.

• Subsections

  • none

• Keywords

  • SECTION_PARAMETERS
  • CUTOFF_W
  • DO_KPOINTS
  • EPS_FILTER
  • EPS_FILTER_FACTOR
  • EPS_STORAGE_SCALING
  • EXP_KPOINTS
  • KPOINTS
  • MEMORY_CUT
  • MEMORY_INFO
  • MIN_BLOCK_SIZE
  • MIN_BLOCK_SIZE_MO

• Keyword descriptions

  SECTION_PARAMETERS
  	&LOW_SCALING {Logical}
  	Activates cubic-scaling RPA, GW and Laplace-SOS-MP2 calculations.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  CUTOFF_W
  	CUTOFF_W {Real}
  	Cutoff for screened Coulomb interaction for GW kpoints.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 5.00000000E-001

  DO_KPOINTS
  	DO_KPOINTS {Logical}
  	Besides in DFT, this keyword has to be switched on if one wants to do kpoints in. cubic RPA.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  EPS_FILTER
  	EPS_FILTER {Real}
  	Determines a threshold for the DBCSR based multiply.Normally, this EPS_FILTER determines accuracy and timing of low-scaling RPA and GW calculations.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-009

  EPS_FILTER_FACTOR
  	EPS_FILTER_FACTOR {Real}
  	Multiply EPS_FILTER with this factor to determine filter epsilon for DBCSR based multiply P(it)=(Mocc(it))^T*Mvirt(it) Default should be kept.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E+001

  EPS_STORAGE_SCALING
  	EPS_STORAGE_SCALING {Real}
  	Scaling factor to scale EPS_FILTER. Storage threshold for compression will be EPS_FILTER*EPS_STORAGE_SCALING.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E-003
  	Alias names for this keyword: EPS_STORAGE

  EXP_KPOINTS
  	EXP_KPOINTS {Real}
  	For kpoints in low-scaling GW, a Monkhorst-Pack mesh is used. Because the screened Coulomb interaction W(k) diverges at the Gamma point with W(k) ~ k^alpha, we adapt the weights of the Monkhorst-Pack mesh to compute int_BZ k^alpha dk (BZ=Brllouin zone) correctly with the Monkhorst-Pack mesh. You can enter here the exponent alpha. For solids, the exponent is -2 (known from plane waves), for 2d periodic systems -1 and for 1d systems W(k) ~ log(1-cos(a*k)) where a is the length of the unit cell in periodic direction. If you enter 1.0, one of these three functions are picked according to the periodicity. If you enter a value bigger than 2.0, the ordinary Monkhorst-Pack mesh with identical weights is chosen.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.00000000E+000

  KPOINTS
  	KPOINTS {Integer} {Integer} {Integer}
  	For periodic calculations, using kpoints for the density response and the Coulomb operator are strongly recommended. For 2d periodic systems (e.g. xy periodicity, please specify KPOINTS N_x 0 N_z.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely 3 integers.
  	Default values: 0 0 0

  MEMORY_CUT
  	MEMORY_CUT {Integer}
  	Reduces memory for sparse tensor contractions by this factor. A high value leads to some loss of performance. This memory reduction factor applies to storage of the tensors 'M occ' / 'M virt' but does not reduce storage of '3c ints'.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 5

  MEMORY_INFO
  	MEMORY_INFO {Logical}
  	Decide whether to print memory info on the sparse matrices.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  MIN_BLOCK_SIZE
  	MIN_BLOCK_SIZE {Integer}
  	Minimum tensor block size. Adjusting this value may have minor effect on performance but default should be good enough.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 5

  MIN_BLOCK_SIZE_MO
  	MIN_BLOCK_SIZE_MO {Integer}
  	Tensor block size for MOs. Only relevant for GW calculations. The memory consumption of GW scales as O(MIN_BLOCK_SIZE_MO). It is recommended to set this parameter to a smaller number if GW runs out of memory. Otherwise the default should not be changed.  [Edit on GitHub]
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 64