Parameter file

Parameter file syntax

The parameter file is split up to blocks of parameters. Each parameter block begins with a line

# Block: BLOCKNAME

Anything in the parameter file followed by a # sign is taken to be a comment, except for the block name definitions. Block name definitions begin with a # followed by the word Block, a colon and then the actual name of the block.

Block names are followed by the lines containing the parameters and their values. Each parameter definition contains three parts, name of the parameter, value and some explanatory comment:

PARAMETER_NAME = PARAMETER_VALUE  # PARAMETER_DESCRIPTION

Long expressions and comments can be broken into multiple lines with a backslash (\) at the end of of the broken line.

In reality a parameter block for the radiation sources can looks like this:

# -----------------------------------------------------------------------------
# Block: Radiation sources
# -----------------------------------------------------------------------------
incl_cont_stellarsrc      = False  # # Switches on (True) or off (False) continuous stellar sources )
incl_disc_stellarsrc      = True  # # Switches on (True) or off (False) discrete stellar sources)
mstar                     = [1.0*ms]  # # Mass of the star(s)
pstar                     = [0.0, 0.0, 0.0]  # # Position of the star(s) (cartesian coordinates)
rstar                     = [2.0*rs]  # # Radius of the star(s)
tstar                     = [4000.0]  # # Effective temperature of the star(s) [K]

List of blocknames

  • Radiation sources
  • Grid parameters
  • Dust opacity
  • Gas line RT
  • Code parameters
  • Model

These block-names should not be modified as the reader function will look for these strings.

Radiation sources

  • incl_disc_stellarsrc : list
    Switches on (True) or off (False) discrete stellar radiation sources.
  • mstar : list
    Mass of the star. Each element of the list contains the mass of an individual star as a float.
  • pstar : list
    Coordinates of the star. Each element of the list contains a three element vector containing the 3D cartesian coordinates of each individual star.
  • rstar : list
    Stellar radius. Each element of the list contains the radius of an individual star as a float.
  • tstar : list
    Effective temperature. Each element of the list contains the effective temperature of an individual star as a float.
  • incl_cont_stellarsrc : list
    Switches on (True) or off (False) continuous stellar radiation sources
    NOTE, the model should have the appropriate functions (getStellarsrcDensity(), getStellarsrcTemplates())

Grid

  • crd_sys : {‘sph’, ‘car’}
    Coordinate system type
  • nw : list
    Number of wavelength points in the wavelength grid, nw[i] sets the number of grid points in the [wbound[i], wbound[i+1]) interval (or on the [wbound[-2], wbound[-1]] for the last interval)
  • nx : list
    Number of grid cells in the first spatial coordinate, nx[i] sets the number of grid points in the [xbound[i], xbound[i+1]) interval (or on the [xbound[-2], xbound[-1]] for the last interval)
  • ny : list
    Number of grid cells in the second spatial coordinate, ny[i] sets the number of grid points in the [ybound[i], ybound[i+1]) interval (or on the [ybound[-2], ybound[-1]] for the last interval)
  • nz : list
    Number of grid cells in the third spatial coordinate, nz[i] sets the number of grid points in the [zbound[i], zbound[i+1]) interval (or on the [zbound[-2], zbound[-1]] for the last interval)
  • wbound : list
    Boundaries of the wavelength grid
  • xbound : list
    Boundaries of the spatial grid in the first coordinate, nx[i] sets the number of grid points in the [xbound[i], xbound[i+1]) interval (or on the [xbound[-2], xbound[-1]] for the last interval)
  • xres_nlev : float
    Radial grid refinement in spherical coordinate system
  • xres_nspan : float
    Radial grid refinement in spherical coordinate system
  • xres_nstep : int
    Radial grid refinement in spherical coordinate system
  • ybound : list
    Boundaries of the spatial grid in the second coordinate, ny[i] sets the number of grid points in the [ybound[i], ybound[i+1]) interval (or on the [ybound[-2], ybound[-1]] for the last interval)
  • zbound : list
    Boundaries of the spatial grid in the third coordinate, nz[i] sets the number of grid points in the [zbound[i], zbound[i+1]) interval (or on the [zbound[-2], zbound[-1]] for the last interval)

Separable mesh refinement

Spatial and wavelength grid definitions allow ‘separable mesh refinement’, i.e. refinement of the wavelength or the spatial mesh along individual axes. Let us take now the wavelength grid for an example. If we wish to cover the \(10^{-2}-10^4\mu{\rm m}\) interval with 200 grid points we should set wbound = [0.01, 1e4] and nw = [200]. This results in a logarithmic wavelength grid between wbound[0] and wbound[1] containing nw[0] grid points. This wavelenght grid might be fine enough to sample the radiation field of the sources and the thermal emission of the dust in the model, but too coarse to study e.g. the shape of the silicate features in the mid-infrared. If we are interested in the silicate feature around \(10\mu{\rm m}\) only, we can refine this region in the wavelength grid by setting wbound = [0.01, 7.5, 13.5, 1e4] and nw = [50,100,50]. This grid setup will result in 50, 100, 50 grid points in the \([0.01\mu{\rm m},7.5\mu{\rm m})\), \([7.5\mu{\rm m},13.5\mu{\rm m})\) , \([13.5\mu{\rm m},10^4\mu{\rm m}]\) intervals, respectively.

Note, the number of grid points are defined always on a right-open interval, except in the last, rightmost interval, where the interval is closed.

Grid refinement at the inner boundary

Even for logarithmic radial grids the innermost parts of the model can still be optically thick for centrally concentrated density distributions. With the use of the xres_nlev, xres_nspan and xres_nstep parameters we can introduce additional grid refinement in the radial grid of a spherical coordinate system. The grid refinement is done in the following way. First a logarithmic radial grid is set up on the basis of the nx and xbound parameters. Then the interval between the innermost cell interface and the xres_nspan th cell interface (i.e. xres_nspan-1 grid cell) will be taken and split into xres_nlev grid cells. Then the innermost grid cell will be split into xres_nlev ‘new’ grid cells, then again the innermost, refined grid cell will be taken and split into xres_nlev cells. The splitting of the innermost cell will be done xres_nstep times.

Dust opacity

  • dustkappa_ext : str
    File name tag in the dust opacity file. Dust opacity files should have names like e.g., dustkappa_EXT.inp, where the dustkappa_ext parameter should contain the ‘EXT’ tags from the file name (e.g. for dustkappa_ext = 'silicate' the dust opacity file should be dustkappa_silicate.inp.
  • gdens : float
    Bulk density of the material
  • gsdist_powex : float
    Grain size distribution power exponent
  • gsmax : float
    Maximum grain size in the distribution
  • gsmin : float
    Minimum grain size in the distribution
  • lnk_fname : list
    File name list (including full path) containing optical constants (NOTE, the file should contain three columns: wavelength [micron], n, k)
  • mixabun : list
    If multiple species specified their mass absorption coefficients can be mixed according to the mixing ratios (mass fractions) in mixabun.
  • ngs : float
    Number of grain sizes in the grain size distribution

Gas lines

  • gasspec_colpart_abun : float
    Abundance of the collisional partner
  • gasspec_colpart_name : float
    Name of the collisional partner
  • gasspec_mol_abun : float
    Molecular abundance
  • gasspec_mol_dbase_type : {‘leiden’, ‘linelist’}
    Database type of the molecular data (see the RADMC-3D manual for the definitions of various formats).
  • gasspec_mol_name : str
    Name of the molecular species whose lines should be calculated

Code

  • istar_sphere : int
    If 0 discrete stars are taken to be point-like, if 1 the finite extent of the star is taken into account
  • itemdecoup : int
    Allows (0) or prevents (1) the decoupling of the temperature of different dust species
  • lines_mode : int
    Line mode (for the definitions of the individual line modes see the RADMC-3D manual):
    • 1 - LTE
    • 2 - User-defined populations I
    • 3 - LVG populations
    • 4 - Optically thin NLTE level populations method
    • 5 - User-defined populations II
  • nphot : int
    Number of photons in the thermal Monte Carlo simulations
  • nphot_scat : int
    Number of photons used for the scattering Monte Carlo simulations when images are calculated
  • nphot_spec : int
    Number of photons used for the scattering Monte Carlo simultaions when SEDs/spectra are calculated
  • rto_style : int
    Output format: 1 - Formatted ASCII, 3 - C-style binary
  • scattering_mode_max : int
    Scattering mode :
    • 0 - Scattering is switched off
    • 1 - Isotropic scattering
    • 2 - Anysotropic scattering with Henyey-Greenstein phase function
    • 3 - Anysotropic scattering with tabulated phase function
    • 4 - Anysotropic scattering with polarization but the full scattering matrix is only used for the last scattering
    • 5 - Anysotropic scattering with scattering matrix, full treatment
  • tgas_eq_tdust : int
    Dust temperature is taken to be the gas kinetic temperature
  • modified_random_walk : int
    Switches on (1) and off (0) modified random walk