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Manual: Add links to RI-HFX page

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Ole Schütt 2024-01-26 14:24:08 +01:00 • committed by Ole Schütt
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docs/methods/dft/ri_hfx.md
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@ -57,8 +57,9 @@ with a large basis, and a small dense system. Different input options are shown
In this example, a geometry optimization of the glycine molecule is calculated at the Hartree-Fock
level of theory, with the cc-pVQZ basis set (taken from https://www.basissetexchange.org). The RI
basis set, referred to as `RI_HFX` in the `&KIND` input section, is explicitly provided by the user
in this example. It takes about 70 seconds to run on 16 CPUs, per geometry optimization step.
basis set, referred to as `RI_HFX` in the [KIND](#CP2K_INPUT.FORCE_EVAL.SUBSYS.KIND) input section,
is explicitly provided by the user in this example. It takes about 70 seconds to run on 16 CPUs, per
geometry optimization step.
There are a couple take home messages with this example:
@ -70,99 +71,100 @@ There are a couple take home messages with this example:
$(\mu\sigma\lfloor P)$, which is only really useful in PBCs.
In this specific example, RI-HFX is much more efficient than the original 4-center implementation.
You can try running the same input with the `&HF%RI` section commented out for a demonstration.
You can try running the same input with the [HF/RI](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI) section
commented out for a demonstration.
```none
&GLOBAL
PROJECT glycine
PRINT_LEVEL MEDIUM
RUN_TYPE GEO_OPT
&END GLOBAL
&FORCE_EVAL
METHOD Quickstep
&DFT
BASIS_SET_FILE_NAME BASIS_cc-pVQZ
POTENTIAL_FILE_NAME POTENTIAL
!Sort basis function accoring to their exponent for more sparsity
SORT_BASIS EXP
&MGRID
CUTOFF 500
REL_CUTOFF 50
NGRIDS 5
&END MGRID
&QS
!all-electron calculations require GAPW
METHOD GAPW
&END QS
&POISSON
!non-periodic calculation for this molecule
PERIODIC NONE
PSOLVER WAVELET
&END
&SCF
EPS_SCF 1.0E-6
MAX_SCF 50
&END SCF
&XC
&XC_FUNCTIONAL NONE
&END XC_FUNCTIONAL
&HF
!Pure RI Hartree-Fock calculation using only defaults:
! -HFX potential is the 1/r Coulomb interaction
! -RI metric is also the 1/r Coulomb interaction
! -Default accuracy parameters (good in most cases)
&RI
&END RI
&END HF
&END XC
&END DFT
&SUBSYS
&CELL
ABC 10.0 10.0 10.0
PERIODIC NONE
&END CELL
&COORD
C -0.04879702 -0.00000000 1.40419128
N -1.35021542 0.00000000 2.04225544
C -0.04354337 0.00000000 -0.12235209
O -1.02422569 -0.00000000 -0.83489570
O 1.22983691 0.00000000 -0.61028238
H 1.14837668 -0.00000000 -1.58391528
H 0.53209836 -0.87421885 1.73662058
H 0.53209836 0.87421885 1.73662058
H -1.88873390 0.81280508 1.74087629
&GLOBAL
PROJECT glycine
PRINT_LEVEL MEDIUM
RUN_TYPE GEO_OPT
&END GLOBAL
&FORCE_EVAL
METHOD Quickstep
&DFT
BASIS_SET_FILE_NAME BASIS_cc-pVQZ
POTENTIAL_FILE_NAME POTENTIAL
!Sort basis function accoring to their exponent for more sparsity
SORT_BASIS EXP
&MGRID
CUTOFF 500
REL_CUTOFF 50
NGRIDS 5
&END MGRID
&QS
!all-electron calculations require GAPW
METHOD GAPW
&END QS
&POISSON
!non-periodic calculation for this molecule
PERIODIC NONE
PSOLVER WAVELET
&END
&SCF
EPS_SCF 1.0E-6
MAX_SCF 50
&END SCF
&XC
&XC_FUNCTIONAL NONE
&END XC_FUNCTIONAL
&HF
!Pure RI Hartree-Fock calculation using only defaults:
! -HFX potential is the 1/r Coulomb interaction
! -RI metric is also the 1/r Coulomb interaction
! -Default accuracy parameters (good in most cases)
&RI
&END RI
&END HF
&END XC
&END DFT
&SUBSYS
&CELL
ABC 10.0 10.0 10.0
PERIODIC NONE
&END CELL
&COORD
C -0.04879702 -0.00000000 1.40419128
N -1.35021542 0.00000000 2.04225544
C -0.04354337 0.00000000 -0.12235209
O -1.02422569 -0.00000000 -0.83489570
O 1.22983691 0.00000000 -0.61028238
H 1.14837668 -0.00000000 -1.58391528
H 0.53209836 -0.87421885 1.73662058
H 0.53209836 0.87421885 1.73662058
H -1.88873390 0.81280508 1.74087629
H -1.88873390 -0.81280508 1.7408762
&END COORD
&TOPOLOGY
!Always a good idea to put the molecule in the middle of the simulation cell in non-PBCs
&CENTER_COORDINATES
&END CENTER_COORDINATES
&END TOPOLOGY
&KIND C
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&KIND O
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&KIND N
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&KIND H
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&END SUBSYS
&TOPOLOGY
!Always a good idea to put the molecule in the middle of the simulation cell in non-PBCs
&CENTER_COORDINATES
&END CENTER_COORDINATES
&END TOPOLOGY
&KIND C
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&KIND O
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&KIND N
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&KIND H
BASIS_SET cc-pVQZ
BASIS_SET RI_HFX cc-pVQZ-JKFIT
POTENTIAL ALL
&END KIND
&END SUBSYS
&END FORCE_EVAL
```
@ -182,76 +184,77 @@ There are a handful of take home messages with this example:
- Always use HFX potentials that decay within half the simulation cell in periodic HFX calculations
- Using short range RI metrics is crucial for performance
- ADMM is available in all its flavors, and it helps reducing computational costs
- Using the keyword `SORT_BASIS EXP` helps create sparsity and improves performance
- Setting the keyword [SORT_BASIS](#CP2K_INPUT.FORCE_EVAL.DFT.SORT_BASIS) to `EXP` helps create
sparsity and improves performance
- Automatically generated RI basis sets are very accurate, although larger and less efficient than
pre-optimized ones
```none
&GLOBAL
PROJECT Si64
RUN_TYPE ENERGY
&END GLOBAL
&FORCE_EVAL
&DFT
BASIS_SET_FILE_NAME BASIS_ccGRB_UZH
BASIS_SET_FILE_NAME BASIS_ADMM_UZH
&GLOBAL
PROJECT Si64
RUN_TYPE ENERGY
&END GLOBAL
&FORCE_EVAL
&DFT
BASIS_SET_FILE_NAME BASIS_ccGRB_UZH
BASIS_SET_FILE_NAME BASIS_ADMM_UZH
POTENTIAL_FILE_NAME POTENTIAL_UZH
!sort the basis function according to their exponent for more sparsity
!sort the basis function according to their exponent for more sparsity
SORT_BASIS EXP
!generate the RI_HFX basis set on the fly
AUTO_BASIS RI_HFX SMALL
AUTO_BASIS RI_HFX SMALL
!turn on ADMM
&AUXILIARY_DENSITY_MATRIX_METHOD
ADMM_TYPE ADMMS
&END AUXILIARY_DENSITY_MATRIX_METHOD
&MGRID
CUTOFF 600
REL_CUTOFF 50
NGRIDS 5
&END MGRID
&SCF
EPS_SCF 1.0E-6
MAX_SCF 40
&END SCF
&XC
&XC_FUNCTIONAL
&PBE
SCALE_X 0.75
&END PBE
&END XC_FUNCTIONAL
&HF
FRACTION 0.25
&AUXILIARY_DENSITY_MATRIX_METHOD
ADMM_TYPE ADMMS
&END AUXILIARY_DENSITY_MATRIX_METHOD
&MGRID
CUTOFF 600
REL_CUTOFF 50
NGRIDS 5
&END MGRID
&SCF
EPS_SCF 1.0E-6
MAX_SCF 40
&END SCF
&XC
&XC_FUNCTIONAL
&PBE
SCALE_X 0.75
&END PBE
&END XC_FUNCTIONAL
&HF
FRACTION 0.25
&INTERACTION_POTENTIAL
!Important to use a limited range potential in periodic HFX
!Important to use a limited range potential in periodic HFX
POTENTIAL_TYPE TRUNCATED
!5.4 < half cell dimension
CUTOFF_RADIUS 5.4
&END
CUTOFF_RADIUS 5.4
&END
&RI
!overlap metric for maximal efficiency
RI_METRIC IDENTITY
&END RI
&END HF
&END XC
&END DFT
&SUBSYS
&CELL
ABC 10.861395 10.861395 10.861395
&END CELL
&TOPOLOGY
COORD_FILE_FORMAT XYZ
COORD_FILE_NAME ./Si64.xyz
&END TOPOLOGY
&KIND Si
BASIS_SET ccGRB-D-q4
BASIS_SET AUX_FIT admm-dzp-q4
POTENTIAL GTH-PBE0-q4
&END KIND
&END SUBSYS
!overlap metric for maximal efficiency
RI_METRIC IDENTITY
&END RI
&END HF
&END XC
&END DFT
&SUBSYS
&CELL
ABC 10.861395 10.861395 10.861395
&END CELL
&TOPOLOGY
COORD_FILE_FORMAT XYZ
COORD_FILE_NAME ./Si64.xyz
&END TOPOLOGY
&KIND Si
BASIS_SET ccGRB-D-q4
BASIS_SET AUX_FIT admm-dzp-q4
POTENTIAL GTH-PBE0-q4
&END KIND
&END SUBSYS
&END FORCE_EVAL
```
@ -260,21 +263,22 @@ There are a handful of take home messages with this example:
There are some few input parameters of particular importance when running RI-HFX, mostly concerning
the efficiency to accuracy balance. Here is a list:
- `RI_METRIC`: the choice of RI metric is crucial for performance in periodic calculations. A
shorter ranged RI metric will generally be more efficient, while a longer ranged metric (e.g. TC
with a cutoff radius of 1.5 Angstrom) can be more accurate. See [](#Bussy2023) for a full
discussion.
- `EPS_FILTER`: the bottleneck of the RI-HFX calculation consists of sparse tensor contractions.
This parameter is the threshold for block sparsity during calculations, with a safe default of
$1.0\times10^{-9}$. A looser threshold might significantly speedup calculations (not recommended
to go higher than $1.0\times10^{-8}$).
- `MEMORY_CUT`: this keyword influences the batching strategy for large tensor contractions. In
RI-HFX, some tensor contractions are done in multiple steps, with large intermediate results.
Storing these intermediates can lead to memory shortage. The value of `MEMORY_CUT` (default of 3)
indicates how large tensors are split into batches, such that smaller intermediates can be stored.
Note that MEMORY_CUT 3 does not mean that the total memory consumption of the program is divided
by three (initial and final tensors are not affected, as well as the data concerning the rest of
the calculation). A higher value reduces the memory footprint, but leads to performance overheads.
- [RI_METRIC](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.RI_METRIC): the choice of RI metric is crucial for
performance in periodic calculations. A shorter ranged RI metric will generally be more efficient,
while a longer ranged metric (e.g. TC with a cutoff radius of 1.5 Angstrom) can be more accurate.
See [](#Bussy2023) for a full discussion.
- [EPS_FILTER](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.EPS_FILTER): the bottleneck of the RI-HFX
calculation consists of sparse tensor contractions. This parameter is the threshold for block
sparsity during calculations, with a safe default of $1.0\times10^{-9}$. A looser threshold might
significantly speedup calculations (not recommended to go higher than $1.0\times10^{-8}$).
- [MEMORY_CUT](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.MEMORY_CUT): this keyword influences the batching
strategy for large tensor contractions. In RI-HFX, some tensor contractions are done in multiple
steps, with large intermediate results. Storing these intermediates can lead to memory shortage.
The value of [MEMORY_CUT](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.MEMORY_CUT) (default of 3) indicates
how large tensors are split into batches, such that smaller intermediates can be stored. Note that
`MEMORY_CUT 3` does not mean that the total memory consumption of the program is divided by three
(initial and final tensors are not affected, as well as the data concerning the rest of the
calculation). A higher value reduces the memory footprint, but leads to performance overheads.
Most other keywords have little to no importance, and their default values are fine.
@ -352,10 +356,10 @@ input. The matrices are diagonalized, and their eigenvalues used as band energie
[cp2k_bs2csv](https://github.com/cp2k/cp2k-output-tools) to transform the resulting CP2K output to a
more workable CSV file.
Note that in this input file, we select a value of $1.0\times 10^{-6}$ for `EPS_PGF_ORB`. This
parameter controls the range of AOs, and threfore the extent of the local atom-specific RI basis
sets. This value leads to particularly high accuracy. The default of $1.0\times 10^{-5}$ is
typically enough.
Note that in this input file, we select a value of $1.0\times 10^{-6}$ for
[EPS_PGF_ORB](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.EPS_PGF_ORB). This parameter controls the range of
AOs, and threfore the extent of the local atom-specific RI basis sets. This value leads to
particularly high accuracy. The default of $1.0\times 10^{-5}$ is typically enough.
The HFX potential was selected as the Truncated Coulomb operator with a cutoff radius of $R_C = 5.0$
Angstroms. As for all periodic HFX calculations, a limited range potential is required. In case of
@ -373,131 +377,135 @@ affect speed in RI-HFXk, while insuring best possible accuracy.
As for most HFX calculations, the SCF convergence can be spedup by restarting from a converged PBE
wavefunction. Note that in k-point restart files, the real-space density matrices are dumped.
However, many more images are required for HFX calculation than for PBE, due to the non-locality of
exact-exchange. Using a very tight value of `EPS_PGF_ORB` (e.g. $1.0\times 10^{-12}$) in the initial
PBE calculation leads to a lot of images there as well. An example is provided in the example file
[bundle](https://www.cp2k.org/_media/howto:ri_hfx_examples.zip). The example bellow takes about 5
minutes to run on 32 CPUs if restarted from a PBE wavefunction, and 10 minutes otherwise.
exact-exchange. Using a very tight value of
[EPS_PGF_ORB](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.EPS_PGF_ORB) (e.g. $1.0\times 10^{-12}$) in the
initial PBE calculation leads to a lot of images there as well. An example is provided in the
example file [bundle](https://www.cp2k.org/_media/howto:ri_hfx_examples.zip). The example bellow
takes about 5 minutes to run on 32 CPUs if restarted from a PBE wavefunction, and 10 minutes
otherwise.
```none
&GLOBAL
PROJECT graphene_kp
RUN_TYPE ENERGY
&GLOBAL
PROJECT graphene_kp
RUN_TYPE ENERGY
&END GLOBAL
&FORCE_EVAL
&DFT
BASIS_SET_FILE_NAME BASIS_pob
POTENTIAL_FILE_NAME POTENTIAL
SORT_BASIS EXP
AUTO_BASIS RI_HFX MEDIUM
!restarting from a converged PBE calculation lead to less SCF steps
WFN_RESTART_FILE_NAME graphene_pbe-RESTART.kp
!Turning on the ADMM approximation
&AUXILIARY_DENSITY_MATRIX_METHOD
ADMM_TYPE ADMMS
&END AUXILIARY_DENSITY_MATRIX_METHOD
&FORCE_EVAL
&DFT
BASIS_SET_FILE_NAME BASIS_pob
POTENTIAL_FILE_NAME POTENTIAL
SORT_BASIS EXP
AUTO_BASIS RI_HFX MEDIUM
!restarting from a converged PBE calculation lead to less SCF steps
WFN_RESTART_FILE_NAME graphene_pbe-RESTART.kp
!Turning on the ADMM approximation
&AUXILIARY_DENSITY_MATRIX_METHOD
ADMM_TYPE ADMMS
&END AUXILIARY_DENSITY_MATRIX_METHOD
&QS
!sometimes necessary when running small systems with a lot of CPUs
PW_GRID_BLOCKED FALSE
METHOD GAPW
!needs to be the same value as that in RI%EPS_PGF_ORB
EPS_PGF_ORB 1.0E-6
PW_GRID_BLOCKED FALSE
METHOD GAPW
!needs to be the same value as that in RI%EPS_PGF_ORB
EPS_PGF_ORB 1.0E-6
&END QS
&MGRID
CUTOFF 600
REL_CUTOFF 60
NGRIDS 5
&END MGRID
&SCF
EPS_SCF 1.0E-06
&MGRID
CUTOFF 600
REL_CUTOFF 60
NGRIDS 5
&END MGRID
&SCF
EPS_SCF 1.0E-06
MAX_SCF 50
!typically need lower threshold to start DIIS with k-points
EPS_DIIS 0.05
SCF_GUESS RESTART
&END SCF
&XC
&XC_FUNCTIONAL
&PBE
SCALE_X 0.75
&END
&END XC_FUNCTIONAL
&HF
FRACTION 0.25
&RI
KP_NGROUPS 16
!using a smaller than default EPS_PGF_ORB allows for a
!more accurate calculation with a larger local RI basis
EPS_PGF_ORB 1.0E-6
&END RI
&INTERACTION_POTENTIAL
!Always use a limited ranged potential in PBCs
POTENTIAL_TYPE TRUNCATED
CUTOFF_RADIUS 5.0
!typically need lower threshold to start DIIS with k-points
EPS_DIIS 0.05
SCF_GUESS RESTART
&END SCF
&XC
&XC_FUNCTIONAL
&PBE
SCALE_X 0.75
&END
&END XC_FUNCTIONAL
&HF
FRACTION 0.25
&RI
KP_NGROUPS 16
!using a smaller than default EPS_PGF_ORB allows for a
!more accurate calculation with a larger local RI basis
EPS_PGF_ORB 1.0E-6
&END RI
&INTERACTION_POTENTIAL
!Always use a limited ranged potential in PBCs
POTENTIAL_TYPE TRUNCATED
CUTOFF_RADIUS 5.0
&END INTERACTION_POTENTIAL
&END HF
&END XC
&KPOINTS
SCHEME MONKHORST-PACK 19 19 1
&END XC
&KPOINTS
SCHEME MONKHORST-PACK 19 19 1
&END KPOINTS
&PRINT
&BAND_STRUCTURE
ADDED_MOS 5
&KPOINT_SET
NPOINTS 50
SPECIAL_POINT GAMMA 0.0000000000 0.0000000000 0.0000000000
SPECIAL_POINT M 0.5000000000 0.0000000000 0.0000000000
SPECIAL_POINT K 0.3333333333 0.3333333333 0.0000000000
SPECIAL_POINT GAMMA 0.0000000000 0.0000000000 0.0000000000
&PRINT
&BAND_STRUCTURE
ADDED_MOS 5
&KPOINT_SET
NPOINTS 50
SPECIAL_POINT GAMMA 0.0000000000 0.0000000000 0.0000000000
SPECIAL_POINT M 0.5000000000 0.0000000000 0.0000000000
SPECIAL_POINT K 0.3333333333 0.3333333333 0.0000000000
SPECIAL_POINT GAMMA 0.0000000000 0.0000000000 0.0000000000
&END KPOINT_SET
FILE_NAME graphene_kp.bs
&END BAND_STRUCTURE
FILE_NAME graphene_kp.bs
&END BAND_STRUCTURE
&END PRINT
&END DFT
&SUBSYS
&CELL
!enough space between 2 sheets of graphene not to interact
ABC 2.46 2.46 20.000
ALPHA_BETA_GAMMA 90.0 90.0 120.0
&END CELL
&COORD
SCALED
C 0.3333333 0.6666667 0.000
C 0.6666667 0.3333333 0.000
&END COORD
&KIND C
BASIS_SET pob-TZVP-rev2
BASIS_SET AUX_FIT pob-DZVP-rev2
POTENTIAL ALL
&END KIND
&END SUBSYS
&END FORCE_EVAL
&END DFT
&SUBSYS
&CELL
!enough space between 2 sheets of graphene not to interact
ABC 2.46 2.46 20.000
ALPHA_BETA_GAMMA 90.0 90.0 120.0
&END CELL
&COORD
SCALED
C 0.3333333 0.6666667 0.000
C 0.6666667 0.3333333 0.000
&END COORD
&KIND C
BASIS_SET pob-TZVP-rev2
BASIS_SET AUX_FIT pob-DZVP-rev2
POTENTIAL ALL
&END KIND
&END SUBSYS
&END FORCE_EVAL
```
### Important input parameters
There are a few important input parameters for RI-HFXk calculations:
- `EPS_FILTER`: the filtering threshold for sparse tensors. Works the same way as for $\Gamma$-point
calculations (see above).
- `RI_METRIC`: using the default value for the RI metric, which correspond to the choice of HFX
potential, is the way to go. It insures best possible accuracy, while only marginally increasing
the costs.
- `NGROUPS`: this is a performance keyword. During the calculation of the real-space exact-exchange
matrices, the work is split among MPI subcommunicators. Using more groups drastically speeds up
the calculation (efficienctly up to 16 groups, reasonably up to 32). This comes with a memory
overhead though, as some data must be replicated on each subgroup. The total number of MPI ranks
must be divisible by the number of groups.
- `EPS_PGF_ORB`: generally determines the range of GTOs in the AO basis. As such, it also determines
the extent of the local atom-specific RI basis used for RI-HFXk. The default value of
$1.0\times 10^{-5}$ has proven to be accurate and fast.
- `KP_USE_DELTA_P`: when set to .TRUE. (default value), the next SCF step is calculated using the
density matrix difference, rather than the full new density matrix. This helps with computational
efficiency by increasing sparsity. If your calculation struggles to converge, you can try to turn
this off.
- [EPS_FILTER](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.EPS_FILTER): the filtering threshold for sparse
tensors. Works the same way as for $\Gamma$-point calculations (see above).
- [RI_METRIC](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.RI_METRIC): using the default value for the RI
metric, which correspond to the choice of HFX potential, is the way to go. It insures best
possible accuracy, while only marginally increasing the costs.
- [KP_NGROUPS](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.KP_NGROUPS): this is a performance keyword. During
the calculation of the real-space exact-exchange matrices, the work is split among MPI
subcommunicators. Using more groups drastically speeds up the calculation (efficienctly up to 16
groups, reasonably up to 32). This comes with a memory overhead though, as some data must be
replicated on each subgroup. The total number of MPI ranks must be divisible by the number of
groups.
- [EPS_PGF_ORB](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.EPS_PGF_ORB): generally determines the range of
GTOs in the AO basis. As such, it also determines the extent of the local atom-specific RI basis
used for RI-HFXk. The default value of $1.0\times 10^{-5}$ has proven to be accurate and fast.
- [KP_USE_DELTA_P](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI.KP_USE_DELTA_P): when set to .TRUE. (default
value), the next SCF step is calculated using the density matrix difference, rather than the full
new density matrix. This helps with computational efficiency by increasing sparsity. If your
calculation struggles to converge, you can try to turn this off.
The rest of the `&HF%RI` input parameters related to k-point sampling (all with a KP\_ prefix) have
little to no impact, and their default values are good enough.
The rest of the [HF/RI](#CP2K_INPUT.ATOM.METHOD.XC.HF.RI) input parameters related to k-point
sampling (all with a KP\_ prefix) have little to no impact, and their default values are good
enough.