qrunch.common.constants.chemistry
Numerical constants shared across qrunch.chemistry library code.
Module Attributes
Cutoff for considering determinants as significant in the trim configuration interaction calculator. |
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Maximum hydrogen-acceptor distance (Angstrom) for a pair to be considered a hydrogen bond. |
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Minimum donor-hydrogen-acceptor angle (degrees) for a pair to be considered a hydrogen bond. |
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Distance change (Angstrom) that maps to a unit contribution in the combined hydrogen-bond score. |
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Angle change (degrees) that maps to a unit contribution in the combined hydrogen-bond score. |
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Maximum deviation from nominal full occupation for an orbital to still be included in the active space. |
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Threshold for treating small anomalous occupation deviations as noise when selecting active spaces. |
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MOs whose squared projection onto the target AOs exceeds this are active. |
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Relative eigenvalue threshold for pruning directions when reducing two-body integrals to an active space. |
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Minimum eigenvalue threshold for inclusion when double-factorizing electron repulsion integrals. |
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Number of molecular orbitals above which lazy integrals are used when an active-space modifier is present. |
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Numerical offset used to keep occupation-sorting values inside open interval boundaries. |
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Energy convergence tolerance for the mean-field (HF/DFT) SCF step. |
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Gradient convergence tolerance for the mean-field (HF/DFT) SCF step. |
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Maximum number of SCF iterations for the mean-field (HF/DFT) step. |
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Threshold below which virtual natural orbitals are discarded in post-HF (CCSD/MP2) calculators. |
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Virtual orbitals with HF orbital energies above this threshold are disregarded in post-HF calculators. |
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Maximum number of stability-check / re-convergence cycles when UHF stability analysis is enabled. |
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Minimum allowed gap between any occupied and virtual orbital energy for MP2-based calculators. |
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Maximum allowed absolute value of any off-diagonal Fock matrix element, matching default SCF convergence. |
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Coefficients (or CI convergence deltas) below this magnitude are treated as negligible/zero. |
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Default cap on the number of neighboring-state overlaps returned when exploring the CI subspace. |
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MP2 amplitudes below this magnitude are omitted from the initial wavefunction. |
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Convergence threshold for the cost-function change in Pipek-Mezey-style orbital localization. |
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Power used to define the localization norm in Pipek-Mezey-style localizers. |
- ACTIVE_SPACE_NOISE_TOLERANCE = 0.0001
Threshold for treating small anomalous occupation deviations as noise when selecting active spaces.
- ACTIVE_SPACE_OCCUPATION_DEVIATION_THRESHOLD = 0.02
Maximum deviation from nominal full occupation for an orbital to still be included in the active space.
- AVAS_SELECTION_THRESHOLD = 0.2
MOs whose squared projection onto the target AOs exceeds this are active.
- Type:
AVAS truncation threshold
- CANONICALITY_TOLERANCE = 1e-06
Maximum allowed absolute value of any off-diagonal Fock matrix element, matching default SCF convergence.
- DETERMINANT_CUTOFF = 1e-10
Cutoff for considering determinants as significant in the trim configuration interaction calculator.
- DOUBLE_FACTORIZED_INTEGRALS_TOLERANCE = 1e-10
Minimum eigenvalue threshold for inclusion when double-factorizing electron repulsion integrals.
- HYDROGEN_BOND_ACCEPTOR_MAX_DISTANCE_ANGSTROM = 2.5
Maximum hydrogen-acceptor distance (Angstrom) for a pair to be considered a hydrogen bond.
- HYDROGEN_BOND_ANGLE_CHANGE_SCALE_DEGREES = 30.0
Angle change (degrees) that maps to a unit contribution in the combined hydrogen-bond score.
- HYDROGEN_BOND_DISTANCE_CHANGE_SCALE = 0.3
Distance change (Angstrom) that maps to a unit contribution in the combined hydrogen-bond score.
- HYDROGEN_BOND_MINIMUM_ANGLE_DEGREES = 120.0
Minimum donor-hydrogen-acceptor angle (degrees) for a pair to be considered a hydrogen bond.
- INTEGRAL_REDUCTION_TOLERANCE = 1e-10
Relative eigenvalue threshold for pruning directions when reducing two-body integrals to an active space.
- LAZY_INTEGRAL_THRESHOLD = 120
Number of molecular orbitals above which lazy integrals are used when an active-space modifier is present.
- LOCALIZATION_CONVERGENCE_TOLERANCE = 1e-06
Convergence threshold for the cost-function change in Pipek-Mezey-style orbital localization.
- LOCALIZATION_EXPONENT_DEFAULT = 2
Power used to define the localization norm in Pipek-Mezey-style localizers.
- MEAN_FIELD_CONVERGENCE_TOLERANCE = 1e-09
Energy convergence tolerance for the mean-field (HF/DFT) SCF step.
- MEAN_FIELD_CONVERGENCE_TOLERANCE_GRADIENT = 3.1622776601683795e-05
Gradient convergence tolerance for the mean-field (HF/DFT) SCF step.
- MEAN_FIELD_MAX_ITERATIONS = 50
Maximum number of SCF iterations for the mean-field (HF/DFT) step.
- MP2_DEGENERACY_THRESHOLD = 0.1
Minimum allowed gap between any occupied and virtual orbital energy for MP2-based calculators.
- MP2_WAVEFUNCTION_AMPLITUDE_THRESHOLD = 1e-08
MP2 amplitudes below this magnitude are omitted from the initial wavefunction.
- NEGLIGIBLE_COEFFICIENT_TOLERANCE = 1e-12
Coefficients (or CI convergence deltas) below this magnitude are treated as negligible/zero.
- OCCUPATION_SORTING_BORDER_EPSILON = 1e-12
Numerical offset used to keep occupation-sorting values inside open interval boundaries.
- POST_HF_FROZEN_VIRTUAL_THRESHOLD = 100.0
Virtual orbitals with HF orbital energies above this threshold are disregarded in post-HF calculators.
- POST_HF_MAX_STABILITY_ITERATIONS = 10
Maximum number of stability-check / re-convergence cycles when UHF stability analysis is enabled.
- POST_HF_VIRTUAL_TRUNCATION_THRESHOLD = 1e-05
Threshold below which virtual natural orbitals are discarded in post-HF (CCSD/MP2) calculators.
- SUBSPACE_DIAGONALIZATION_MAX_OVERLAPS = 1000
Default cap on the number of neighboring-state overlaps returned when exploring the CI subspace.