Charge Conservation
The Charge Conservation node adds the equations for charge conservation according to Gauss’ law for the electric displacement field. It provides an interface for defining the constitutive relation and its associated properties such as the relative permittivity.
Material Type
The Material type setting decides how materials behave and how material properties are interpreted when the mesh is deformed. Select Solid for materials whose properties change as functions of material strain, material orientation, and other variables evaluated in a material reference configuration (material frame). Select Nonsolid for materials whose properties are defined only as functions of the current local state at each point in the spatial frame, and for which no unique material reference configuration can be defined. Select From material to pick up the corresponding setting from the domain material on each domain.
Constitutive Relation D-E
Select a Dielectric model to describe the macroscopic properties of the medium (relating the electric displacement D with the electric field E) and the applicable material properties, such as the relative permittivity. Select:
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Relative permittivity (the default) to use the constitutive relation D = ε0εrE. Then the default is to take the Relative permittivity εr (dimensionless) values From material.  For User defined, select Isotropic, Diagonal, Symmetric, or Full and enter values or expressions in the field or matrix. The default is 1.
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Polarization to use the constitutive relation D = ε0E + P. Then enter the components based on space dimension for the Polarization vector P (SI unit: C/m2). The defaults are 0 C/m2.
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Remanent electric displacement to use constitutive relation D = ε0εrE + Dr, where Dr is the remanent displacement (the displacement when no electric field is present). Then the default is to take the Relative permittivity εr (dimensionless) values From material.  For User defined, select Isotropic, Diagonal, Symmetric, or Full and enter values or expressions in the field or matrix. Then enter the components based on space dimension for the Remanent electric displacement Dr (SI unit: C/m2). The defaults are 0 C/m2.
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Dispersion to use the constitutive relation D = ε0E + P(E, εrS), where the polarization vector is calculated from the electric field using the dielectric dispersion model. This option is available when the Material type is set to Solid. You enter the Relative permittivity εrS (dimensionless) values From material.  For User defined, select Isotropic, Diagonal, or Symmetric and enter values or expressions in the field or matrix. This value of electric permittivity will be used in stationary study, for which the polarization vector is calculated as P= ε0(εrS − Ι)E.
Once this option is selected, a subnode Dispersion will become available under the Charge Conservation node. At that subnode, you can select the dispersion model, enter the corresponding parameters, and chose how the relative permittivity input on the parent node will be interpreted in Eigenfrequency, Frequency Domain and Time Dependent studies.