Defining a System in Console Mode

Defining a system means to select the chemical components and to retrieve thermodynamic data about those components from an appropriate database in order to do the calculations. You use database(s) with thermodynamic data and then define what system elements as components. Once the system is defined, you retrieve the system’s thermodynamic data from the database(s).

  • If you use a response-driven module to perform your calculation, such as BIN or POURBAIX, then the module prompts you to select database(s) and define the system.
  • When doing calculations in the POLY module, you typically have to manually select databases and define the system in the DATA module. However, it is also possible to define the system directly in POLY using the DEFINE_MATERIAL and DEFINE_DIAGRAM commands.

Database (TDB) Module Commands

  1. Go to the DATA (TDB) module. At the SYS prompt, use GOTO_MODULE and enter Data.
  2. Change the default database unless you directly specify the name of the database as a parameter to the command. Type SWITCH_DATABASE and follow the prompts.

    The second part of the command prompt indicates the current default database. For example, if the prompt is TDB_TCFE10, then the current database is TCFE10.

  3. Use DEFINE_ELEMENTS followed by a list of the elements that you want in your system. (To list the elements that are available in your current database, use LIST_DATABASE and choose Elements). For example, if you want to have Fe and C in your system, type:

    DEFINE_ELEMENTS Fe C

  4. Use REJECT and choose Phases if you want to avoid retrieving any phases from the database. (To list the phases that are available in your current database, use LIST_DATABASE and choose Phases. To list the phases that can form in the defined system, use LIST_SYSTEM and choose Constituent.) For example, if you do not want the graphite phase to be retrieved, you type:

    REJECT PHASES GRAPHITE

    If the number of phases to include is much lower than the total number of phases, then it can be convenient to first Reject Phases * and then restore the phases to include using Restore Phases.

  5. Use GET_DATA to search the database and send the thermodynamic data about your system to the GIBBS workspace.

    At this point you can proceed to the POLY module (with Goto_module POLY). However, you may want to add elements, phases and species to the GIBBS workspace from other databases. If so, then proceed to the next step.

  6. Use APPEND_DATABASE to select the (additional) database from which you want to retrieve data. This command works exactly in the same way as the SWITCH_DATABASE command, with the exception that it does not reinitialize the DATA module and the GIBBS workspace, but instead appends or replaces the data that has already been retrieved with new data from the additional database.
  7. Define your elements and specify whether to reject and restore any phases. Do this in exactly the same way when using the SWITCH_DATABASE command (see steps 2 and 3).
  8. Use GET_DATA to search the database and add the thermodynamic data to the data that already exists in the GIBBS workspace.
  9. Use APPEND_DATABASE again if you want to add data from yet another database. When you have retrieved all the data you need, you can proceed to the POLY module.