Physical Property Backbone

Purpose: Shared base classes for physical-property types and their common metadata structure

In scope:

• PhysicalProperty as the common base for computed properties
• ErrorEstimate subsection used for uncertainty/error metadata
• Abstract/base property families for electronic, Green-function, energy, force, and spectral data
• Cross-domain backbone used by specialized output verticals

Relationship map

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classDiagram
    class BaseElectronicEigenvalues
    class BaseEnergy
    class BaseForce
    class BaseGreensFunction
    class Energy2
    class ErrorEstimate
    class Frequency
    class ImaginaryTime
    class MatsubaraFrequency
    class PhysicalProperty
    class SpectralProfile
    class Time
    class WignerSeitz
    PhysicalProperty <|-- BaseElectronicEigenvalues
    PhysicalProperty <|-- BaseEnergy
    PhysicalProperty <|-- BaseForce
    PhysicalProperty <|-- BaseGreensFunction
    PhysicalProperty <|-- SpectralProfile
    BaseGreensFunction --> Frequency : real_frequency
    BaseGreensFunction --> ImaginaryTime : imaginary_time
    BaseGreensFunction --> MatsubaraFrequency : matsubara_frequency
    BaseGreensFunction --> Time : time
    BaseGreensFunction --> WignerSeitz : wigner_seitz
    PhysicalProperty --> ErrorEstimate : errors
    SpectralProfile --> Energy2 : energies
    SpectralProfile --> Energy2 : frequencies

Legend

Parent <|-- Child inheritance (Child extends Parent)

Owner --> SubSection containment/subsection

Key sections

Section	Description	MetaInfo
PhysicalProperty	A base section for computational output properties, containing all relevant (meta)data.	Open in MetaInfo browser
ErrorEstimate	A generic container for uncertainty/error information associated with a PhysicalProperty.	Open in MetaInfo browser
BaseElectronicEigenvalues	A base section used to define basic quantities for the ElectronicEigenvalues and ElectronicBandStructure properties.	Open in MetaInfo browser
BaseGreensFunction	A base class used to define shared commonalities between Green's function-related properties.	Open in MetaInfo browser
BaseEnergy	Abstract class used to define a common value quantity with the appropriate units for different types of energies, which avoids repeating the definit...	Open in MetaInfo browser
BaseForce	Base class used to define a common value quantity with the appropriate units for different types of forces, which avoids repeating the definitions f...	Open in MetaInfo browser
SpectralProfile	A base section used to define the spectral profile.	Open in MetaInfo browser

Quantities by section

PhysicalProperty

Quantity	Type	Description
name	m_str(str)	Name of the physical property. Example: 'ElectronicBandGap'.
iri	URL	Internationalized Resource Identifier (IRI) pointing to a definition, typically within a larger, ontological framework.
type	m_str(str)	Type categorization of the physical property. Example: an ElectronicBandGap can be 'direct' or 'indirect'.
contribution_type	m_str(str)	Type of contribution to the physical property. Hence, only applies to contributions instances. Example: TotalEnergy may have contributions like kinetic, potential, etc.
label	m_str(str)	Label for additional classification of the physical property. Example: an ElectronicBandGap can be labeled as 'DFT' or 'GW' depending on the methodology used to calculate it.
entity_ref		Reference to the entity that the physical property refers to. Reference to the entity that the physical property refers to. Examples: - a simulated physical property might refer to the macroscopic system or instead of a specific atom in the unit cell. In the first case, outputs.model_system_ref (see outputs.py) will point to the ModelSystem section, while in the second case, entity_ref will point to AtomsState section (see atoms_state.py).
is_derived	m_bool(bool)	Flag indicating whether the physical property is derived from other physical properties. Flag indicating whether the physical property is derived from other physical properties. We make the distinction between directly parsed and derived physical properties: - Directly parsed: the physical property is directly parsed from the simulation output files. - Derived: the physical property is derived from other physical properties. No extra numerical settings are required to calculate the physical property.
physical_property_ref		Reference to the PhysicalProperty section from which the physical property was derived. If physical_property_ref is populated, the quantity is_derived is set to True via normalization.
is_scf_converged	m_bool(bool)	Flag indicating whether the physical property is converged or not after a SCF process. This quantity is connected with SelfConsistency defined in the numerical_settings.py module.
self_consistency_ref		Reference to the SelfConsistency section that defines the numerical settings to converge the physical property (see numerical_settings.py).

ErrorEstimate

Quantity	Type	Description
metric	Enum	The type of error or uncertainty metric being reported. The type of error or uncertainty metric being reported. Allowed values are: | Value | Description | |-------------------|-----------------------------------------------------------------------------| | "std" | Standard deviation of the observable. | | "stderr" | Standard error of the mean (std / √N). | | "variance" | Variance of the observable (σ²). | | "rmse" | Root-mean-square error between predictions and reference values. | | "mae" | Mean absolute error between predictions and reference values. | | "mape" | Mean absolute percentage error, expressed relative to reference values. | | "ci" | Confidence interval for the observable, typically with a specified level. | | "pi" | Prediction interval for new observations. | | "iqr" | Interquartile range (Q3 – Q1). | | "mad" | Median absolute deviation (robust alternative to standard deviation). | | "systematic_bias" | Estimated systematic offset (bias) between observed and true values. | | "model_uncertainty" | Uncertainty arising from the model itself (e.g., ML predictive spread). | | "other" | A different metric not covered above; further specified in notes or definition_iri. |
definition_iri	m_str(str)	IRI/URL pointing to a formal metric definition.
method	m_str(str)	Computation method for the estimate (e.g., bootstrap, jackknife, analytical).
n_samples	m_int32(int32)	Number of samples used to compute the estimate (if applicable).
scope	Enum	The application scope of the estimate: The application scope of the estimate: - global: single number applies to the whole property; - per_value: array aligned with the property's value array; - per_component: aligned with a named component axis (see component_axis); - per_entity: aligned with referenced entities.
component_axis	m_str(str)	Name of the component axis this estimate aligns to (used with scope=per_component).
value	m_float64(float64) (shape: ['*'])	Error/uncertainty values for metrics such as std, stderr, rmse, mae, etc.
interval_type	Enum	Type of interval if an interval is provided.
level	m_float64(float64)	Interval level (e.g., 0.95 for 95% intervals).
lower	m_float64(float64) (shape: ['*'])	Lower bound of the interval (scalar or array aligned to the target).
upper	m_float64(float64) (shape: ['*'])	Upper bound of the interval (scalar or array aligned to the target).
bias	m_float64(float64) (shape: ['*'])	Estimated systematic bias (scalar or array).
notes	m_str(str)	Free-text provenance or remarks about the estimate.

BaseElectronicEigenvalues

Quantity	Type	Description
n_levels	m_int32(int32)	Number of energy levels per sampling point. Number of energy levels per sampling point. In periodic systems these correspond to electronic bands; in molecular calculations they correspond to (spin-resolved) molecular orbitals or similar one-particle states.
value	m_float64(float64) (shape: ['', ''])	Value of the electronic eigenvalues.

BaseGreensFunction

Quantity	Type	Description
n_atoms	m_int32(int32)	Number of atoms involved in the correlations effect and used for the matrix representation of the property. Can be derived from entity_ref if needed.
entity_ref		Reference to the ElectronicState section describing the correlated orbitals for which the Green's function properties are calculated. The parent AtomsState can be accessed via entity_ref.get_parent_entity().
spin_channel	m_int32(int32)	Spin channel of the corresponding electronic property. It can take values of 0 and 1.
local_model_type	Enum	Type of Green's function calculated from the mapping of the local Hubbard-Kanamo... Type of Green's function calculated from the mapping of the local Hubbard-Kanamori model into the Anderson impurity model. The impurity Green's function describe the electronic correlations for the impurity, and it is a local function. The lattice Green's function includes the coupling to the lattice and hence it is a non-local function. In DMFT, the lattice term is approximated to be the impurity one, so that these simulations are converged if both types of the local part of the lattice Green's function coincides with the impurity Green's function.
space_id	Enum	String used to identify the space in which the Green's function property is represented. String used to identify the space in which the Green's function property is represented. The spaces are: | space_id | variable type | | ------ | ------ | | 'r' | WignerSeitz | | 'rt' | WignerSeitz + Time | | 'rw' | WignerSeitz + Frequency | | 'rit' | WignerSeitz + ImaginaryTime | | 'riw' | WignerSeitz + MatsubaraFrequency | | 'k' | KMesh | | 'kt' | KMesh + Time | | 'kw' | KMesh + Frequency | | 'kit' | KMesh + ImaginaryTime | | 'kiw' | KMesh + MatsubaraFrequency | | 't' | Time | | 'it' | Frequency | | 'w' | ImaginaryTime | | 'iw' | MatsubaraFrequency |

BaseEnergy

Quantity	Type	Description
value	m_float64(float64)	No description available.

BaseForce

Quantity	Type	Description
value	m_float64(float64) (shape: ['', ''])	No description available.

SpectralProfile

Quantity	Type	Description
value	m_float_bounded(float) (shape: ['*'])	The value of the intensities of a spectral profile. Must be positive.