The Legolas parfile allows for a full customisation of all Legolas variables, and most of these have default values. Legolas explicitly inspects your equilibrium for nonsensical values and will warn you if something is not right. Whenever the code catches something during its inspection phase it either logs a warning and continues running, or exits with an error depending on the severity of the issue.

You can create the parfile manually using this guide, or let Pylbo take care of generating one. More information on generating parfiles with Pylbo can be found here.


This namelist includes all grid-related variables.

Warning: For cylindrical geometries we override the start value with $r = 0.025$ if it is initialised with zero. Some matrix elements scale with $1/r$ and may become very large when $r \rightarrow 0$, resulting in very large elements which may throw off some solvers. Note that the matrix elements and equilibria are evaluated in the Gaussian grid, the first point of which may be very small but will never be exactly zero.

Setting force_r0 = .true. in the gridlist forces the r = 0 condition, but this is not recommended.

Parameter Type Description Default value
geometry string geometry of the setup "Cartesian"
gridpoints int number of gridpoints in the base grid 50
x_start real starting point of the base grid 0
x_end real end point of the base grid 1
coaxial logical use a coaxial inner boundary in cylindrical geometry .false.
force_r0 logical forces r=0 in cylindrical geometry .false.
symmetric_grid logical enforces grid symmetry around the centre of the interval (for use with a symmetric spacing function) .false.


This namelist includes all equilibrium-related variables.

Parameter Type Description Default value
equilibrium_type string the equilibrium configuration to use, see the various options. Set to "user_defined" to use a custom configuration. "adiabatic_homo"
boundary_type string boundary conditions to use "wall"
use_defaults logical if .true., uses the default values in the equilibrium submodule .true.


This namelist includes all physics-related variables.

Parameter Type Description Default value
physics_type string physics type to use, can be {"mhd", "hd", "hd-1d"} "mhd"
basis_functions list basis functions corresponding to the state vector components, options are {"quadratic", "cubic"}. By default ($\rho_1$, $v_2$, $v_3$, $T_1$, $a_1$) are "quadratic", ($v_1$, $a_2$ and $a_3$) are "cubic". -
mhd_gamma real ratio of specific heats $\gamma$ $\frac{5}{3}$
incompressible logical whether to use the incompressible approximation, this sets $\gamma = 10^{12}$ and eliminates some matrix elements .false.
flow logical inclusion of background flow effects .false.
radiative_cooling logical whether to include optically thin radiative losses .false.
ncool int number of points used when interpolating cooling curves 4000
cooling_curve string which cooling curve to use, can be {"nothing", "jc_corona", "dalgarno", "dalgarno2", "ml_solar", "spex", "spex_dalgarno", "rosner", "colgan", "colgan_dm"}. In the case of "nothing" you should define your own $\Lambda(T)$ cooling function and its temperature derivative. "nothing"
heating logical whether to include background heating .false.
force_thermal_balance logical whether to set the heating in such a way to enforce thermal equilibrium .true.
external_gravity logical whether to include external gravity .false.
parallel_conduction logical whether to include parallel thermal conduction .false.
fixed_tc_para_value real  if given (and not 0) a constant value for the parallel thermal conduction will be used 0
perpendicular_conduction logical whether to include perpendicular thermal conduction .false.
fixed_tc_perp_value real  if given (and not 0) a constant value for the perpendicular thermal conduction will be used 0
resistivity logical whether to include resistivity .false.
fixed_resistivity_value real  if given (and not 0) a constant value for the resistivity will be used 0
use_eta_dropoff logical if .true., smoothly drops off the resistivity profile to zero near the edges using a hyperbolic tangent profile .false.
viscosity logical whether to include viscosity .false.
viscosity_value real constant value for the viscosity  0
viscous_heating  logical whether to include viscous heating .false.
hall_mhd  logical whether to include Hall MHD effects .false.
hall_dropoff logical if .true. the Hall MHD profile is smoothly dropped off to zero near the edges using a hyperbolic tangent profile .false.
elec_inertia logical whether to include electron inertia .false.
inertia_dropoff logical if .true. the electron inertia profile is smoothly dropped off to zero near the edges using a hyperbolic tangent profile .false.
electron_fraction real fraction of electrons in the plasma 0.5
dropoff_edge_dist real  distance between the grid edge and the smoothened dropoff profile 0
dropoff_width real the width over which the profile is smoothened 0


This namelist includes all solver-related variables. For more information, see Solvers

Parameter Type Description Default value
solver string which solver to use, can be {"none", "arnoldi", "QR-invert", "QR-cholesky", "QZ-direct", "inverse-iteration"} "QR-invert"
arpack_mode string the mode for arpack (Arnoldi) "general"
which_eigenvalues string which eigenvalues to calculate (Arnoldi). Can be {"LM", "SM", "LR", "SR", "LI", "SI"} "LM"
number_of_eigenvalues int number of eigenvalues ($k$) to calculate (Arnoldi)  10
maxiter  int maximum number of iterations (Arnoldi, shift-invert) max(100, 10N)
ncv int  number of basis vectors to use (Arnoldi) max(k+1, min(2k, N))
tolerance real  tolerance for eigenvalue convergence (Arnoldi, shift-invert) $5 \times 10^{-15}$
sigma complex shift in the complex plane for iterative methods (Arnoldi, shift-invert) NaN + NaNj


This namelist includes all units-related variables, all units are in cgs. Defaults are set from a unit temperature, unit magnetic field and unit length.

Parameter Type Description Default value
unit_numberdensity real sets the unit number density in cm$^{-3}$ -
unit_density real sets the unit density in g cm$^{-3}$ -
unit_temperature real sets the unit temperature in K $10^6$
unit_magneticfield real sets the unit magnetic field in Gauss $10$
unit_length real sets the unit length in cm $ 10^9$
mean_molecular_weight real the mean molecular weight to use 0.5


This namelist includes all variables related to data output.

Note: Legolas uses a logging-based system to write information to the console, similar to Python’s logging module. The level of output is controlled through the integer logging_level:

  • level 0 : only critical errors are printed, everything else is suppressed.
  • level 1 : only critical errors and warnings are printed
  • level 2 : prints info messages, warnings and critical errors (default)
  • level 3 : (or higher) prints debug messages in addition to all of the above
Parameter Type Description Default value
write_matrices logical whether to write the matrices to the datfile .false.
write_eigenvectors logical whether to write the eigenvectors to the datfile .false.
write_residuals logical  whether to write the residuals to the datfile .false.
write_background logical whether to write the background to the datfile .true.
write_eigenfunctions logical whether to write the eigenfunctions to the datfile .true.
write_derived_eigenfunctions logical  whether to write the derived eigenfunctions to the datfile .false.
write_eigenfunction_subset logical if .true. only writes eigenfunctions for eigenvalues inside a given radius around a point in the complex plane .false.
eigenfunction_subset_radius real radius of the subset NaN
eigenfunction_subset_center complex  center of the subset NaN + NaNj
show_results logical whether to call the Pylbo script after the run .true.
basename_datfile string basename of the datfile "datfile"
 output_folder string  folder to write the datfile to "output"
 logging_level int  controls console information, see note above 2


This namelist handles constant parameters which are used in the equilibrium prescriptions. This is meant to be used in parameter studies, for a comprehensive list of all the possible parameters we refer to this page in the Legolas source code documentation. To see which parameters are used in which equilibria, take a look here.

Note: setting a variable with the paramlist does NOT automatically include it in the equilibrium configuration. For this to have any effect you have to use that variable in your submodule as well. For example, if you never set a magnetic field in your submodule and never use the cte_B02 variable, setting cte_B02 = 1.0d0 in the paramlist will have no effect. Take a look at the different equilibria to see which parameters are supported.