Introduction

Codes

Benchmark

Results
PRE-Benchmark
POST-Data
POST-Plots

Documents

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The PDR Comparison Benchmark

benchmark request.txt

A total of 8 different model clouds were agreed upon for the benchmark comparison. The density and FUV parameter space is covered exemplary by accounting for low and high densities and FUV fields under isothermal conditions, giving 4 different model clouds. The complexity of the model calculations was reduced by setting the gas and dust temperatures to a given constant value (models F1-F4, ’F’ denoting a fixed temperature), making the results independent of the solution of the local energy balance. In a second benchmark set, the thermal balance has been solved explicitly thus determining the temperature profile of the cloud (models V1-V4, ’V’ denoting variable temperatures). The next table gives an overview of the cloud parameter of all eight benchmark clouds.

F1 T=const Tgas=50 K, Tdust=20 K n=10^3 cm^-3, \chi=10	F2 T=const Tgas=50 K, Tdust=20 K n=10^3 cm^-3, \chi=10^5
F3 T=const Tgas=50 K, Tdust=20 K n=10^5.5 cm^-3, \chi=10	F4 T=const Tgas=50 K, Tdust=20 K n=10^3 cm^-3, \chi=10^5
V1 T=variable n=10^3 cm^-3, \chi=10	V2 T=variable n=10^3 cm^-3, \chi=10^5
V3 T=variable n=10^5.5 cm^-3, \chi=10	V4 T=variable n=10^5.5 cm^-3, \chi=10^5

Benchmark Chemistry

One of the crucial steps in arriving at a useful code comparison was to agree on the use of a standardized set of chemical species and reactions to be accounted for in the benchmark calculations. For the benchmark models we only included the four most abundant elements H, He, O, and C. Additionally only the species givenbelow are included in the chemical network calculations:

H, H⁺, H₂, H₂⁺ , H₃⁺,
O, O⁺, OH⁺, OH, O₂, O₂⁺,
H₂O, H₂O⁺, H₃O⁺,
C, C⁺, CH, CH⁺, CH₂, CH₂⁺ , CH₃, CH₃⁺,
CH₄, CH₄⁺, CH₅⁺, CO, CO⁺, HCO⁺, He, He⁺, e^-

 

The full reaction rate file is available as TXT file.