AMEND_PHASE_DESCRIPTION
This command is for the Gibbs Energy System (GES) module.
Also see Solution Models in the GIBBS (GES) Module for detailed information about this command and its options.
Specify/amend phase descriptions if a phase has a miscibility gap, uses a special excess energy model, or has a specific additional contribution to its Gibbs energy, for example.
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Syntax |
AMEND_PHASE_DESCRIPTION |
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Prompts |
Phase name: <Phase name> Specify the name of the phase. Amend what /Composition_Set/: <Subject> Several subjects for the phase can be amended but most often this command is used to enter two or more composition sets for a phase. If a phase has a miscibility gap it is necessary to have two composition sets, one for each possible composition that can be stable simultaneously. Enter a question mark at the prompt to get a list of all possibly amended subjects for a phase. |
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There are no additional prompts for DEBYE_HUCKEL, HKF_ELECTROSTATIC, GLASS_TRANSITION, QUASICHEM_FACT00, QUASICHEM_ISRID, REMOVE_ADDITION, and DEFAULT_STABLE. |
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RENAME_PHASE |
New phase name /ABCD/: <Phase name> Give a new phase name for the chosen phase, or press <Enter> to keep the default shown. |
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Site_ratios |
Sites in first sublattice /XX/ : <YY> Sites in second sublattice /XX/ : <YY> Specify the site numbers for each of the prompted sublattices for the current phase. Press <Enter> to accept the previous definitions. |
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New_constituent |
Sublattice /#/: <Sublattice number> Specify the sublattice where the new constituents are located. Species: <Species name> Give a valid species name. |
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Composition_sets |
New highest set number /#/: <Set number n> The default value (#) is usually one higher than the current value. All phases have initially one composition set. If a lower value (i.e. lower than the default one) is given, that specific composition sets are deleted. You cannot take away the first composition set. Major constituent(s) for sublattice #: /AB/: <Major constituent(s)> Specify the new major constituent(s) for the sublattice #, or press <Enter> to accept the default which was automatically set according to the specified composition set of the phase. This prompt is repeated for all available sublattices in the chosen phase. The major constituents in each sublattice can be given. This may simplify giving start values when calculating the equilibrium as phases with miscibility gaps should have different major constituents for each composition set. |
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Major_constituent |
Composition set /1/: <Composition set number> Give the composition set (digit number) for the chosen phase, or press <Enter> if you want to set major constituents for the specified composition set. Major constituent(s) for sublattice #: /AB/: <Major constituent(s)> Specify the new major constituent(s) for the sublattice #, or press <Enter> to accept the default which is automatically set according to the specified composition set of the phase. This prompt is repeated for all available sublattices in the chosen phase for the specified composition set. The major constituents in each sublattice can be specified. This is useful in order to make calculations converge faster and more easily (because it may simplify giving start values when calculating the equilibrium as those phases with miscibility gaps should have different major constituents for each composition set). The databases often set major constituents for several phases automatically when data are retrieved. |
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Fraction_limits |
Element : <el1> Low fraction limit /0/ : <Appropriate low limit> High fraction limit /1/ : <Appropriate high limit > Element : <el2> Low fraction limit /0/ : <Appropriate low limit> High fraction limit /1/ : <Appropriate high limit> Element : <eln> Low fraction limit /0/ : <Appropriate low limit> High fraction limit /1/ : <Appropriate high limit > |
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Magnetic_ordering |
The antiferromagnetic factor /XX/: <YY> Specify the anti-ferromagnetic factor for the chosen phase. This should be –1 for BCC phase and –3 for all other phases (FCC, HCP, etc.). Short range order fraction of the enthalpy /XX/: <YY> The magnetic ordering is a second-order transformation and part of the enthalpy due to this transformation is due to short-range order. This value is the fraction of the total enthalpy that is due to short-range ordering above the magnetic transition temperature. The default value (xx) is 0.40 for BCC phase, and 0.28 for all other phases (FCC, HCP, etc.). |
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Never_disorder |
Never disorder: <Phase name> Give the phase name to never disorder. The contribution from the disordered phase are added to the ordered phase. Use this to avoid entering several parameters to the ordered phase in the database. Instead it can be expressed as one parameter in the disordered phase. |
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Disordered_part |
Disordered phase name: <Phase name> Give the disordered phase name for which there is no ordering sublattice. |
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Excess_model |
Model name /ABCDEFG/: <Model name> The default model is the pre-set model for the solution phase, normally the REDLICH-KISTER_MUGGIANU model, or choose another model for the phase to be amended:
The MIXED-EXCESS-MODELS option has sub-options: First (the independent) constituent: <Constituent name> Second (the dependent) constituent: <Constituent name> Specify the binary pair of constituents in the current substitutional solution phase (the first one as the so-called independent constituent, and the second one as the dependent constituent), for which you wish to change the binary excess model from the default REDLICH-KISTER model to another model (LEGENDRE or POLYNOM). You are prompted with the first sub-option (i.e. Excess model type: /Legendre/: <Desired binary excess model type> For the currently-specified binary pair, choose one the legal binary excess models: LEGENDRE, POLYNOM or REDLICH-KISTER. If the default binary excess model REDLICH-KISTER is used for a certain binary pair, you can either specify the model name (or in short as R-K) or press <Enter>. After this sub-option, it returns to the first sub-option First (the independent) constituent: either for further change(s) of binary excess model of any other binary pair(s) or for termination (by pressing <Enter>) in the MIXED-EXCESS-MODELS option. |
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Ternary_extrapolat |
Extrapolation method: /Toop-Kohler/: <Ternary model> Choose a ternary extrapolation model for the current solution phase:
The TOOP-KOHLER option further prompts: Constituent in sublattice #: <Basis constituent name> First interaction constituent: <Interacting constituent name> Toop constituent: <Toop constituent name> Specify the so-called Kohler constituents (entered as the basis constituent and first interacting constituent) and Toop constituent on a given sublattice in the current solution phase. |
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Quasichem_ionic |
To use the Quasichemical Model for the chosen liquid phase, you must first enter it as an ionic liquid phase, and then use this amending option. It creates a completely new phase, the original IONIC_LIQUID phase remains in the system and is not changed. Number of bonds/atom /2/: <Number of bonds per atom> Specify the Z value (number of bonds per atom). |
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Status_bits |
Correct the phase status bits. It is important to fully understand this command before using it: New status word (in hexadecimal) /04204000/: <New status bits> Normally, these should never be changed in this way, because such phase status bits are automatically set on when all the phase descriptions (predefined in databases and amended in the GIBBS module) are defined properly. The only exceptions are for the Kapoor-Frohberg-Gaye cell model for liquid SLAG solution phase, which can be set only as 04208000; and for the complete Revised HKF AQUEOUS solution model, which can be set as |