Spectroscopic Properties

Purpose: Absorption spectra, XAS, and dielectric response

In scope:

• Spectral profile base class
• Absorption spectra from BSE calculations
• X-ray absorption spectra (XAS) from core hole calculations
• Frequency-dependent dielectric functions (permittivity)

Relationship map

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classDiagram
    class AbsorptionSpectrum
    class Energy2
    class Frequency
    class Permittivity
    class SpectralProfile
    class XASSpectrum
    SpectralProfile <|-- AbsorptionSpectrum
    AbsorptionSpectrum <|-- XASSpectrum
    Permittivity --> Frequency : frequencies
    SpectralProfile --> Energy2 : energies
    SpectralProfile --> Energy2 : frequencies
    XASSpectrum --> AbsorptionSpectrum : exafs_spectrum
    XASSpectrum --> AbsorptionSpectrum : xanes_spectrum

Legend

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

Owner --> SubSection containment/subsection

Key sections

Section	Description	MetaInfo
SpectralProfile	A base section used to define the spectral profile.	Open in MetaInfo browser
AbsorptionSpectrum		Open in MetaInfo browser
XASSpectrum	X-ray Absorption Spectrum (XAS).	Open in MetaInfo browser
Permittivity	Response of the material to polarize in the presence of an electric field.	Open in MetaInfo browser

Quantities by section

SpectralProfile

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

AbsorptionSpectrum

Quantity	Type	Description
axis	Enum	Axis of the absorption spectrum. This is related with the polarization direction, and can be seen as the principal term in the tensor Permittivity.value (see permittivity.py module).

XASSpectrum

This section has no direct quantities.

Permittivity

Quantity	Type	Description
type	Enum	Type of permittivity which allows to identify if the permittivity depends on the frequency or not.
value	m_complex128(complex) (shape: ['*'])	Value of the permittivity tensor. If the value does not depend on the scattering vector q, then we can extract the optical absorption spectrum from the imaginary part of the permittivity tensor (this is also called macroscopic dielectric function).