Parameters

The HRG equation of state module has a variety of parameters for the calculation of the equation of state. The output file will correspond to the selected parameter choices.

As described in the Quickstart, the user must provide a config.yaml file. The purpose of this file is to supply all the configuration information required to run the module, such as input data and program options. The rules for this input file are specified in the OpenAPI Specifications file provided with the module.

Each time the module is executed, it reads the config.yaml file provided by the user and verifies that the input conforms to the OpenAPI specifications. If it does not, module execution will be unsuccessful. When this happens, make sure to check the logs to identify the issue with your configuration.

It is not necessary to specify every single parameter in the configuration file. Parameters listed under the HRG_parameters and switchers sections are optional: if omitted, they will be automatically assigned the default value indicated in the OpenAPI specifications.

By contrast, all 12 grid parameters listed under the parameters section (T_min, T_max, dT, mu_B_min, mu_B_max, dmu_B, mu_Q_min, mu_Q_max, dmu_Q, mu_S_min, mu_S_max, dmu_S) are required and must always be explicitly provided in the config.yaml file; the module will fail validation if any of them is missing.

Upon successful execution, the module may produce several output files. These are described in the OpenAPI specification as part of the output schema. Not all of these files are created during every run, and some require the user to specify particular options in the config.yaml file.

Below are tables providing a brief overview of module’s input, semi-internal and output parameter files.

Input Parameters

The input parameters required to execute the HRG module are presented in the table below. All parameters have default values in case the user does not specify any. Complete details are given in the module’s OpenAPI specifications.

Category Description	Input Parameter	Description		Required	Default
Parameters	T_min	Minimum temperature (in MeV)		Yes	1.0
	T_max	Maximum temperature (in MeV)		Yes	180.0
	dT	Temperature step size (in MeV)		Yes	5.0
	mu_B_min	Min. baryon chem. potential (in MeV)		Yes	0.0
	mu_B_max	Max. baryon chem. potential (in MeV)		Yes	930.0
	dmu_B	Baryon chem. potential step (in MeV)		Yes	10.0
	mu_Q_min	Min. charge chem. potential (in MeV)		Yes	0.0
	mu_Q_max	Max. charge chem. potential (in MeV)		Yes	120.0
	dmu_Q	Charge chem. potential step (in MeV)		Yes	10.0
	mu_S_min	Min. strangeness chem. pot. (in MeV)		Yes	0.0
	mu_S_max	Max. strangeness chem. pot. (in MeV)		Yes	490.0
	dmu_S	Strangeness chem. pot. step (in MeV)		Yes	10.0
HRG_Parameters	a	VdW attractive param. (in GeV·fm3)		No	0.329
	b	VdW baryon excl.-vol. param. (in fm3)		No	3.42
	bm	VdW meson excl.-vol. param. (in fm3)		No	0.0
	particle_list	Particle list to be used for HRG calculations		No	/Thermal-FIST/input/list/PDG2025/list.dat
	interacting-pions	Switcher for interacting pions model		No	False
Switchers	get_P	Store pressure \(p\)		No	True
	get_E_dens	Store energy density		No	True
	get_s_dens	Store entropy density		No	True
	get_B_dens	Store baryon number density		No	True
	get_Q_dens	Store charge number density		No	True
	get_S_dens	Store strangeness number density		No	True
	get_PressHessianMatrix	Store elements of the pressure Hessian matrix		No	False

Following is an example of an exhaustive config.yaml file for the HRG module:

HRG_parameters:
   a: 0.329
   b: 3.42
   bm: 0.1
   interacting-pions: true
   particle_list: /Thermal-FIST/input/list/PDG2025/list.dat
parameters:
   T_min: 0.0
   T_max: 150.0
   dT: 75.0
   mu_B_min: 0.0
   mu_B_max: 300.0
   dmu_B: 300.0
   mu_Q_min: 0.0
   mu_Q_max: 100.0
   dmu_Q: 100.0
   mu_S_min: 0.0
   mu_S_max: 200.0
   dmu_S: 200.0
switchers:
   get_P: true
   get_E_dens: true
   get_s_dens: true
   get_B_dens: true
   get_Q_dens: true
   get_S_dens: true
   get_PressHessianMatrix: true

Semi-internal variables

Several particle lists are available for the HRG calculations, and can be selected by the user through the particle_list parameter in the HRG_parameters section of the config.yaml file. If not specified, the default particle list is the PDG2025 list (as shown in the parameters summary table above), which includes all hadrons and resonances listed in the Particle Data Group (PDG) tables as of 2025. This list is located in the Thermal-FIST package at /Thermal-FIST/input/list/PDG2025/list.dat.

However, the user is free to select another of the different particle lists available in the /Thermal-FIST/input/list/ folder, as well as providing their own, as long as it is in the correct format. The format of the particle list files is described in the Thermal-FIST documentation, and typically includes information such as particle ID, mass, degeneracy, quantum numbers, and decay width.

Output Parameters

The output files generated by the module are in .csv format, and are stored in the output/ directory.

HRG_output_thermodynamics.csv: this file contains values for thermodynamic observables such as pressure, energy density, charge densities, entropy density, as a function of temperature \(T\) and the conserved charge chemical potentials, i.e. \(\mu_B\), \(\mu_S\) and \(\mu_Q\).

HRG_metadata_thermodynamics.yaml: this file contains the metadata for the thermodynamic output file, describing the structure, types and units of the data.

status.yaml: Provides the status of the module’s execution, including success or error messages.