The CP2K project : input section OT

Section OT

Index of all sections. This section is located at __ROOT__%FORCE_EVAL%DFT%SCF%DIAGONALIZATION%OT.

Sets the various options for the orbital transformation (OT) method. Default settings already provide an efficient, yet robust method. Most systems benefit from using the FULL_ALL preconditioner combined with a small value (0.001) of ENERGY_GAP.Well-behaved systems might benefit from using a DIIS minimizer. This section can not be repeated and can be optional.

This section cites following references: [VandeVondele2003] [Weber2008]

Subsections

None

Section keywords

Keyword descriptions

_SECTION_PARAMETERS_
&OT T
controls the activation of the ot method
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
ALGORITHM
ALGORITHM STRICT
Algorithm to be used for OT
This optional keyword expects a keyword. Default value: STRICT
valid keywords:
  • STRICT: Strict orthogonality: Taylor or diagonalization based algorithm.
  • IRAC: Orbital Transformation based Iterative Refinement of the Approximative Congruence transformation (OT/IRAC).

This keyword cites following references: [VandeVondele2003] [VandeVondele2005] [Weber2008]
IRAC_DEGREE
IRAC_DEGREE 4
The refinement polynomial degree (2, 3 or 4).
This optional keyword expects an integer. Default value: 4
MAX_IRAC
MAX_IRAC 5
Maximum allowed refinement iteration.
This optional keyword expects an integer. Default value: 50
ORTHO_IRAC
ORTHO_IRAC POLY
The orthogonality method.
This optional keyword expects a keyword. Default value: CHOL
valid keywords:
  • CHOL: Cholesky.
  • POLY: Polynomial.
  • LWDN: Loewdin.
EPS_IRAC
EPS_IRAC 1.0E-5
Targeted accuracy during the refinement iteration.
This optional keyword expects a real. Default value: 1.0000000000000000E-10
EPS_IRAC_QUICK_EXIT
EPS_IRAC_QUICK_EXIT 1.0E-2
Only one extra refinement iteration is done when the norm is below this value.
This optional keyword expects a real. Default value: 1.0000000000000001E-05
EPS_IRAC_SWITCH
EPS_IRAC_SWITCH 1.0E-3
The algorithm switches to the polynomial refinement when the norm is below this value.
This optional keyword expects a real. Default value: 1.0000000000000000E-02
ON_THE_FLY_LOC
ON_THE_FLY_LOC T
On the fly localization of the molecular orbitals. Can only be used with OT/IRAC.
This optional keyword expects a logical. Default value: F
MINIMIZER
MINIMIZER DIIS
Minimizer to be used with the OT method
This optional keyword expects a keyword. Default value: CG
valid keywords:
  • SD: Steepest descent: not recommended
  • CG: Conjugate Gradients: most reliable, use for difficult systems. The total energy should decrease at every OT CG step if the line search is appropriate.
  • DIIS: Direct inversion in the iterative subspace: less reliable than CG, but sometimes about 50% faster
SAFE_DIIS
SAFE_DIIS ON
Reject DIIS steps if they point away from the minimum, do SD in that case.
This optional keyword expects a logical. Default value: T
variants: SAFER_DIIS
N_DIIS
N_DIIS 4
Number of history vectors to be used with DIIS
This optional keyword expects an integer. Default value: 7
variants: NDIIS
LINESEARCH
LINESEARCH GOLD
1D line search algorithm to be used with the OT minimizer, in increasing order of robustness and cost. MINIMIZER CG combined with LINESEARCH GOLD should always find an electronic minimum. Whereas the 2PNT minimizer is almost always OK, 3PNT might be needed for systems in which successive OT CG steps do not decrease the total energy.
This optional keyword expects a keyword. Default value: 2PNT
valid keywords:
  • NONE: take fixed lenght steps
  • 2PNT: extrapolate based on 2 points
  • 3PNT: ... or on 3 points
  • GOLD: perform 1D golden section search of the minimum (very expensive)
variants: LINE_SEARCH
STEPSIZE
STEPSIZE 0.4
Initial stepsize used for the line search, sometimes this parameter can be reduced to stablize DIIS or to improve the CG behavior in the first few steps
This optional keyword expects a real. Default value: 1.4999999999999999E-01
GOLD_TARGET
GOLD_TARGET 0.1
Target relative uncertainty in the location of the minimum for LINESEARCH GOLD
This optional keyword expects a real. Default value: 1.0000000000000000E-02
PRECONDITIONER
PRECONDITIONER FULL_ALL
Type of preconditioner to be used with all minimization schemes. They differ in effectiveness, cost of construction, cost of application. Properly preconditioned minimization can be orders of magnitude faster than doing nothing.
This optional keyword expects a keyword. Default value: FULL_KINETIC
valid keywords:
  • FULL_ALL: Most effective state selective preconditioner based on diagonalization, requires the ENERGY_GAP parameter to be an underestimate of the HOMO-LUMO gap. This preconditioner is recommended for almost all systems, except very large systems where make_preconditioner would dominate the total computational cost.
  • FULL_SINGLE_INVERSE: Based on H-eS cholesky inversion, similar to FULL_SINGLE in preconditioning efficiency but cheaper to construct, might be somewhat less robust. Recommended for large systems.
  • FULL_SINGLE: Based on H-eS diagonalisation, not as good as FULL_ALL, but somewhat cheaper to apply.
  • FULL_KINETIC: Cholesky inversion of S and T, fast construction, robust, and relatively good, use for very large systems.
  • FULL_S_INVERSE: Cholesky inversion of S, not as good as FULL_KINETIC, yet equally expensive.
  • SPARSE_DIAG: Only based on atomic blocks, very cheap in construction but quite poor.
  • SPARSE_KINETIC: Toward -sparse- linear solver for T-eS.
  • NONE: skip preconditioning

This keyword cites following reference: [VandeVondele2003]
PRECOND_SOLVER
PRECOND_SOLVER DIRECT
How the preconditioner is applied to the residual.
This optional keyword expects a keyword. Default value: DEFAULT
valid keywords:
  • DEFAULT: the default
  • DIRECT: Cholesky decomposition followed by triangular solve (works for FULL_KINETIC/SINGLE_INVERSE/S_INVERSE)
  • INVERSE_CHOLESKY: Cholesky decomposition followed by explicit inversion (works for FULL_KINETIC/SINGLE_INVERSE/S_INVERSE)
ENERGY_GAP
ENERGY_GAP 0.001
Should be an estimate for the energy gap [a.u.] (HOMO-LUMO) and is used in preconditioning, especially effective with the FULL_ALL preconditioner, in which case it should be an underestimate of the gap (0.001 doing normally fine). For the other preconditioners, making this value larger (0.2) will tame the preconditioner in case of poor initial guesses.
This optional keyword expects a real. Default value: 2.0000000000000001E-01
EPS_TAYLOR
EPS_TAYLOR 1.0E-15
Target accuracy of the taylor expansion for the matrix functions, should normally be kept as is.
This optional keyword expects a real. Default value: 9.9999999999999998E-17
variants: EPSTAYLOR
MAX_TAYLOR
MAX_TAYLOR 5
Maximum order of the Taylor expansion before diagonalisation is prefered, for large parallel runs a slightly higher order could sometimes result in a small speedup.
This optional keyword expects an integer. Default value: 4
ROTATION
ROTATION
Introduce additional variables so that rotations of the occupied subspace are allowed as well, only needed for cases where the energy is not invariant under a rotation of the occupied subspace such as non-singlet restricted calculations or fractional occupations.
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
SCP_DFT
SCP_DFT
Introduce additional self-consistent polarization through additional response basis functions (read in through AUX_BASIS.)
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
SCP_NDDO
SCP_NDDO
Introduce additional self-consistent polarization through response basis set = orbital basis set for NDDO.)
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
ENERGIES
ENERGIES
Optimize orbital energies for use in Fermi-Dirac smearing (requires ROTATION and FD smearing to be active).
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
OCCUPATION_PRECONDITIONER
OCCUPATION_PRECONDITIONER
Preconditioner with the occupation numbers (FD smearing)
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
NONDIAG_ENERGY
NONDIAG_ENERGY
Add a non-diagonal energy penalty (FD smearing)
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
NONDIAG_ENERGY_STRENGTH
NONDIAG_ENERGY_STRENGTH
The prefactor for the non-diagonal energy penalty (FD smearing)
This optional keyword expects a real. Default value: 1.0000000000000000E+00


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