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Documentation: nomad-simulations

Electronic Structure Properties

Electronic Structure Properties¶

Purpose: Electronic eigenvalues, band structures, DOS, band gaps, occupancies, and Fermi surfaces

Relationship map¶

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classDiagram
    class BaseElectronicEigenvalues
    class DOSProfile
    class ElectronicBandGap
    class ElectronicBandStructure
    class ElectronicDensityOfStates
    class ElectronicEigenvalues
    class Energy2
    class FermiSurface
    class Occupancy
    ElectronicEigenvalues <|-- ElectronicBandStructure
    DOSProfile <|-- ElectronicDensityOfStates
    BaseElectronicEigenvalues <|-- ElectronicEigenvalues
    DOSProfile *-- Energy2 : energies
    ElectronicDensityOfStates *-- DOSProfile : projected_dos
    ElectronicDensityOfStates *-- Energy2 : energies
    ElectronicEigenvalues *-- BaseElectronicEigenvalues : contributions

Legend

inheritance (is-a)

composition (has-a)

Quantities by Key Sections¶

`BaseElectronicEigenvalues`¶

Section	Description	MetaInfo
`BaseElectronicEigenvalues`	A base section used to define basic quantities for the `ElectronicEigenvalues` and `ElectronicBandStructure` properties.	Open in MetaInfo browser

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.

`ElectronicEigenvalues`¶

Section	Description	MetaInfo
`ElectronicEigenvalues`		Open in MetaInfo browser

Quantity	Type	Description
`spin_channel`	m_int32(int32)	Spin channel of the corresponding electronic eigenvalues. It can take values of 0 or 1.
`occupation`	m_float64(float64) (shape: ['*', 'n_levels'])	Occupation of the electronic eigenvalues. Occupation of the electronic eigenvalues. This is a number depending whether the `spin_channel` has been set or not. If `spin_channel` is set, then this number is between 0 and 1, where 0 means that the state is unoccupied and 1 means that the state is fully occupied; if `spin_channel` is not set, then this number is between 0 and 2. The shape of this quantity is defined as `[K.n_points, K.dimensionality, n_levels]`, where `K` is a `variable` which can be `KMesh` or `KLinePath`, depending whether the simulation mapped the whole Brillouin zone or just a specific path.
`highest_occupied`	m_float64(float64)	Highest occupied electronic eigenvalue. Together with `lowest_unoccupied`, it defines the electronic band gap.
`lowest_unoccupied`	m_float64(float64)	Lowest unoccupied electronic eigenvalue. Together with `highest_occupied`, it defines the electronic band gap.

`ElectronicBandStructure`¶

Section	Description	MetaInfo
`ElectronicBandStructure`	Accessible energies by the charges (electrons and holes) in the reciprocal space.	Open in MetaInfo browser

Quantity	Type	Description
`reciprocal_cell`	QuantityReference	Reciprocal lattice vectors associated with the k-space sampling used for these eigenvalues, taken from the corresponding `KSpace` numerical settings.

`ElectronicBandGap`¶

Section	Description	MetaInfo
`ElectronicBandGap`	Energy difference between the highest occupied electronic state and the lowest unoccupied electronic state.	Open in MetaInfo browser

Quantity	Type	Description
`type`	Enum	Type categorization of the electronic band gap. This quantity is directly related with `momentum_transfer` as by definition, the electronic band gap is `'direct'` for zero momentum transfer (or if `momentum_transfer` is `None`) and `'indirect'` for finite momentum transfer.
`momentum_transfer`	m_float64(float64) (shape: [2, 3])	If the electronic band gap is `'indirect'`, the reciprocal momentum transfer for... If the electronic band gap is `'indirect'`, the reciprocal momentum transfer for which the band gap is defined in units of the `reciprocal_lattice_vectors`. The initial and final momentum 3D vectors are given in the first and second element. Example, the momentum transfer in bulk Si2 happens between the Γ and the (approximately) X points in the Brillouin zone; thus: `momentum_transfer = [[0, 0, 0], [0.5, 0.5, 0]]`. Note: this quantity only refers to scalar `value`, not to arrays of `value`.
`spin_channel`	m_int32(int32)	Spin channel of the corresponding electronic band gap. It can take values of 0 or 1.
`value`	m_float_bounded(float)	The value of the electronic band gap. This value must be positive.

`DOSProfile`¶

Section	Description	MetaInfo
`DOSProfile`	A base section used to define the `value` of the `ElectronicDensityOfState` property.	Open in MetaInfo browser

Quantity	Type	Description
`value`	m_float_bounded(float) (shape: ['*'])	The value of the electronic DOS. Must be positive.

`ElectronicDensityOfStates`¶

Section	Description	MetaInfo
`ElectronicDensityOfStates`	Number of electronic states accessible for the charges per energy and per volume.	Open in MetaInfo browser

Quantity	Type	Description
`spin_channel`	m_int32(int32)	Spin channel of the corresponding electronic DOS. It can take values of 0 or 1.
`energies_origin`	m_float64(float64)	Energy level denoting the origin along the energy axis, used for comparison and visualization. It is defined as the `ElectronicEigenvalues.highest_occupied_energy`.
`normalization_factor`	m_float64(float64)	Normalization factor for electronic DOS to get a cell-independent intensive DOS. The cell-independent intensive DOS is as the integral from the lowest (most negative) energy to the Fermi level for a neutrally charged system (i.e., the sum of `AtomsState.charge` is zero).

`Occupancy`¶

Section	Description	MetaInfo
`Occupancy`	Electrons occupancy of an atom per orbital and spin.	Open in MetaInfo browser

Quantity	Type	Description
`orbitals_state_ref`	Reference	Reference to the `ElectronicState` section in which the occupancy is calculated. This can reference individual orbitals, orbital manifolds, or hybrid/molecular orbitals. The parent AtomsState can be accessed via `orbitals_state_ref.get_parent_entity()`.
`spin_channel`	m_int32(int32)	Spin channel of the corresponding electronic property. It can take values of 0 and 1.
`value`	m_float64(float64)	Value of the electronic occupancy for the orbital defined by `orbitals_state_ref`. Value of the electronic occupancy for the orbital defined by `orbitals_state_ref`. If `spin_channel` is set, then this number is between 0 and 1, where 0 means that the state is unoccupied and 1 means that the state is fully occupied; if `spin_channel` is not set, then this number is between 0 and 2.

`FermiSurface`¶

Section	Description	MetaInfo
`FermiSurface`	Energy boundary in reciprocal space that separates the filled and empty electronic states in a metal.	Open in MetaInfo browser

Quantity	Type	Description
`n_bands`	m_int32(int32)	Number of bands / eigenvalues.