Materials description

Default materials

By default, Danton models the Earth with only three materials: "Rock", "Water" and "Air". These materials are defined within a Materials Definition File (MDF) in TOML format, as outlined below.

# Default materials used by Danton.

# Standard rock.
# See: https://pdg.lbl.gov/2024/AtomicNuclearProperties/standardrock.html.
[Rock]
density = 2.65E+03 # kg/m3.
composition = "Rk" # Fictitious Rockium atom.

# Pure water but with PREM density (i.e. salted water).
[Water]
density = 1.02E+03 # kg/m3.
composition = "H2O"

# Dry air at sea level atmospheric pressure (mass composition).
[Air]
density = 1.205 # kg/m3.
composition = { C = 0.000124, N = 0.755267, O = 0.231781, Ar = 0.012827 }

Geometry composition

The interior layers of the Earth, in addition to the topography layer, are composed of "Rock" with varying bulk density. The PREM ocean, or oceanic regions, are constituted by "Water". The atmospheric layers are constituted by "Air" with varying density.

Custom materials

It is possible to use custom materials by providing one’s own MDF, with the section titles corresponding to the material names (capitalised, by convention). It is required that each material section indicates the material density (in kg/m³) and its composition. Additionally, the material mean excitation energy (MEE) may be provided using the I attribute (expressed in GeV), if desired.

In the event that the "Rock" "Water" or "Air" material is not defined, Danton will add the corresponding default entry to the MDF. For example, the following file extends the default materials by defining two additional types of rocks, "Limestone" and "Sandstone".

[Limestone]
density = 2.71E+03 # kg/m3.
composition = "CaCO3" # Composition as a chemical formula.

[Sandstone]
density = 2.6E+03 # kg/m3.
composition = { SiO2 = 0.94, Al2O3 = 0.06 } # Using mass fractions.

Note

It is only possible to assign a different material to the topography layer. However, the "Rock", "Water" and "Air" materials can be modified by redefining the corresponding MDF entries.

Composition

The material composition can be expressed in the form of a molecular formula (e.g. "H2O") or by providing a mass composition of atomic elements, molecules, or other materials (see the preceding examples). It should be noted that in the event of a reference to other materials, these must have been defined before within the MDF.