Version: SMASH-2.0
Forced Thermalization

Cell_Number (list of 3 doubles, required, no default):
Number of cells in each direction (x,y,z).

Critical_Edens (double, required, ) Critical energydensity above which forced thermalization is applied, in GeV/fm^3.

Start_Time (double, required, no default):
Time after which forced thermalization may be applied (in fm/c), if energydensity is sufficiently high.

Timestep (double, required, no default):
Timestep of thermalization, in fm/c.

Algorithm (string, optional, default = "biased BF")
Algorithm applied to enforce thermalization. See Oliinychenko:2016vkg [6] for more details.

  • "unbiased BF" - slowest, but theoretically most robust
  • "biased BF" - faster, but theoretically less robust
  • "mode sampling" - fastest, but least robust

Microcanonical (bool, optional, default = false)
Enforce energy conservation or not as part of sampling algorithm. Relevant for biased and unbiased Becattini-Ferroni (BF) algorithms. If this option is on, samples with energies deviating too far from the initial one will be rejected. This is different from simple energy and momentum renormalization, which is done in the end anyway. If energy conservation is enforced at sampling, the distributions become microcanonical instead of canonical. One particular effect is that multiplicity distributions become narrower.

The downside of having this option on is that the sampling takes significantly longer time.

Lattice_Sizes (list of 3 doubles, required, no default):
The lattice is placed such that the center is [0.0,0.0,0.0]. If one wants to have a central cell with center at [0.0,0.0,0.0] then number of cells should be odd (2k+1) in every direction.
Lattice_Sizes is required for all modi, except the box modus. In case of box modus it is set up automatically to match the box size, and the user should not (and is not allowed to) specify it.

Example: Configure Forced Thermalization

Forced Thermalization for certain regions is applied if the corresponding section is present in the configuration file. The following example activates forced thermalization in cells in which the energy density is above 0.3 GeV/fm^3. The lattice is initialized with 21 cells in x and y direction and 101 cells in z-direction. The lattice size is 20 fm in x and y direction and 50 fm in z-direction. The thermalization is applied only for times later than 10 fm with a timestep of 1 fm/c. The sampling is done according to the "biased BF" algorithm.

Forced_Thermalization:
    Lattice_Sizes:    [20.0, 20.0, 50.0]
    Cell_Number:    [21, 21, 101]
    Critical_Edens: 0.3
    Start_Time: 10.0
    Timestep: 1.0
    Algorithm: "biased BF"