# WF_CORRELATION

Section can be repeated.

References: DelBen2012, DelBen2013, DelBen2015, DelBen2015b, Rybkin2016, Wilhelm2016, Wilhelm2016b, Wilhelm2017, Wilhelm2018, Stein2022, Stein2024, Bussy2023

Sets up the wavefunction-based correlation methods as MP2, RI-MP2, RI-SOS-MP2, RI-RPA and GW (inside RI-RPA). [Edit on GitHub]

Subsections

- CANONICAL_GRADIENTS
- INTEGRALS
- LOW_SCALING
- MP2
- PRINT
- RI
- RI_MP2
- RI_RPA
- RI_SOS_MP2

## Keywords

- E_GAP

- E_RANGE

- GROUP_SIZE

- MEMORY

- SCALE_S

- SCALE_T

## Keyword descriptions

E_GAP: real = -1.00000000E+000

  Usage: E_GAP 0.5

  Gap energy for integration grids in Hartree. Defaults to -1.0 (automatic determination). Recommended to set if several RPA or SOS-MP2 gradient calculations are requested or to be restarted. In this way, differences of integration grids across different runs are removed as CP2K does not include derivatives thereof. [Edit on GitHub]

E_RANGE: real = -1.00000000E+000

  Usage: E_RANGE 10.0

  Energy range (ratio of largest and smallest) energy difference of unoccupied and occupied orbitals for integration grids. Defaults to 0.0 (automatic determination). Recommended to set if several RPA or SOS-MP2 gradient calculations are requested or to be restarted. In this way, differences of integration grids across different runs are removed as CP2K does not include derivatives thereof. [Edit on GitHub]

GROUP_SIZE: integer = 1

  Aliases: NUMBER_PROC

  Usage: GROUP_SIZE 2

  Group size used in the computation of GPW and MME integrals and the MP2 correlation energy. The group size must be a divisor of the total number of MPI ranks. A smaller group size (for example the number of MPI ranks per node) accelerates the computation of integrals but a too large group size increases communication costs. A too small group size may lead to out of memory. [Edit on GitHub]

MEMORY: real = 1.02400000E+003

  Usage: MEMORY 1500

  Maximum allowed total memory usage during MP2 methods [MiB]. [Edit on GitHub]

SCALE_S: real = 1.00000000E+000

  Usage: SCALE_S 1.0

  Scaling factor of the singlet energy component (opposite spin, OS) of the MP2, RI-MP2 and SOS-MP2 correlation energy. [Edit on GitHub]

SCALE_T: real = 1.00000000E+000

  Usage: SCALE_T 1.0

  Scaling factor of the triplet energy component (same spin, SS) of the MP2 and RI-MP2 correlation energy. [Edit on GitHub]