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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. Energy level denoting the origin along the energy axis, used for comparison and visualization. This value is fully derived during normalization from the sibling `ElectronicEigenvalues.highest_occupied` (when a resolvable reference is available), so parsers are recommended NOT to populate it directly: any manually set value is recomputed and overwritten on normalization without any logging. Provide `ElectronicEigenvalues.highest_occupied` instead.
`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.