This section in the config.yaml
file contains all general/global configuration options to SMASH.
End_Time
(double, required):
The time in fm after which the evolution is stopped. Note that the starting time depends on the chosen Modus.
Randomseed
(int, required):
Initial seed for the random number generator. If this is negative, the seed will be randomly generated by the operating system.
Nevents
(int, required):
Number of events to calculate.
Use_Grid
(bool, optional, default = true):
true
- A grid is used to reduce the combinatorics of interaction lookup false
- No grid is used.Time_Step_Mode
(string, optional, default = Fixed):
The mode of time stepping. Possible values:
None
- No time steps and no collision-finding grid are used. Cannot be used with potentials. Fixed
- Fixed-sized time steps at which collision-finding grid is used. More efficient for systems with many particles. Metric_Type
(string, optional, default = NoExpansion): NoExpansion
- Default SMASH run, with Minkowski metric MasslessFRW
- FRW expansion going as t^(1/2) MassiveFRW
- FRW expansion going as t^(2/3) Exponential
- FRW expansion going as e^(t/2)Expansion_Rate
(double, optional, default = 0.1):
Corresponds to the speed of expansion of the universe in non minkowski metrics if MetricType is any other than NoExpansion
.
It corresponds to \(b_r/l_0\) if the metric type is MasslessFRW
or MassiveFRW
, and to the parameter b in the Exponential expansion where \(a(t) ~ e^{bt/2}\).
The following example provides a possibility for the General
configuration.
General: Modus: Collider Delta_Time: 0.1 Testparticles: 1 Gaussian_Sigma: 1.0 Gauss_Cutoff_In_Sigma: 3.0 End_Time: 100.0 Randomseed: -1 Nevents: 20 Use_Grid: True Time_Step_Mode: Fixed
In the case of an expanding sphere setup, change the Modus
and provide further information about the expansion.
Modus: Sphere MetricType: MasslessFRW Expansion_Rate: 0.1
Modus
(string, required):
Selects a modus for the calculation, e.g. infinite matter calculation, collision of two particles or collision of nuclei. The modus will be configured in Modi. Recognized values are:
Collider
- For collisions of nuclei or compound objects. See smash::ColliderModus Sphere
- For calculations of the expansion of a thermalized sphere. See smash::SphereModus Box
- For infinite matter calculation in a rectangular box. See smash::BoxModus List
- For given external particle list. See smash::ListModusDelta_Time
(double, optional, default: 1.0):
Time step for the calculation, in fm/c. Not required for timestepless mode.
Testparticles
(int, optional, default = 1):
How many test particles per real particle should be simulated.
Gaussian_Sigma
(double, optional, default = 1.0):
Width of gaussians that represent Wigner density of particles, in fm.
Gauss_Cutoff_In_Sigma
(double, optional, default = 4.0):
Distance in sigma at which gaussian is considered 0.