In the mechanism configuration, the PhaseSpecies struct is defined as follows. micm::Phase stores species as a std::vector<micm::Species>, instead std::vector<PhaseSpecies> and therefore, diffusion coefficient information for species in a given phase is not captured during the conversion from the mechanism configuration type to the micm type. This needs to be implemented.

From mechanism configuration

      struct PhaseSpecies
      {
        std::string name;
        std::optional<double> diffusion_coefficient;
        /// @brief Unknown properties, prefixed with two underscores (__)
        std::unordered_map<std::string, std::string> unknown_properties;
      };

      struct Phase
      {
        std::string name;
        std::vector<PhaseSpecies> species;
        /// @brief Unknown properties, prefixed with two underscores (__)
        std::unordered_map<std::string, std::string> unknown_properties;
      };

Acceptance criteria

• The changes from Set the temporary value for diffusion coefficient #846 are reverted in favor of a better solution

Ideas

• Update the micm::Phase class
• Updates the test