MTDATA – Phase Diagram Software from the National Physical Laboratory







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displays on the screen the current status of the system in terms of which elements, components, substances and phases are present.






list system = elements substances !

list system = components settings phases !

Parameter values:


ELEMENTS displays a list of elements present in the chosen system.

COMPONENTS displays the components together with useful status information:

      1       Al                  NORMAL     undefined
      2       Si                  NORMAL     undefined
      3       Zn                  NORMAL     undefined

No entries in this table can be altered by CLASSIFY.  Columns 3 and 4 have significance only in the calculation modules; their meaning is explained in the relevant manuals.

SUBSTANCES   displays all substances that have been obtained from the database search:

      1       Al                      NORMAL           DEMO_B
      2       Al<FCC_A1>              NORMAL           DEMO_B
      3       Al<HCP_A3>              NORMAL           DEMO_B
      4       Al<LIQUID>              NORMAL           DEMO_B
      5       Al<g>                   NORMAL           DEMO_B
      6       Si<BCC_A2>              NORMAL           DEMO_B
      7       Si<DIAMOND_A4>          NORMAL           DEMO_B
      8       Si<FCC_A1>              NORMAL           DEMO_B
      9       Si<LIQUID>              NORMAL           DEMO_B
     10       Zn<FCC_A1>              NORMAL           DEMO_B
     11       Zn<HCP_A3>              NORMAL           DEMO_B
     12       Zn<LIQUID>              NORMAL           DEMO_B
Substances are constrained to be NORMAL if retrieved from a database for the first time, and ABSENT if a data set for that substance has already been retrieved. The status EX-SYSTEM indicates that the substance cannot be formed from a linear combination of the components, even if the substance does belong to the system of elements.

PHASES   displays a list of all phases.

    NUMBER    PHASE                   STATUS      MODEL
      1       Al                      NORMAL      PURE SUBSTANCE
      2       FCC_A1                  NORMAL      PURE SUBSTANCE
      3       HCP_A3                  NORMAL      PURE SUBSTANCE
      4       LIQUID                  NORMAL      PURE SUBSTANCE
      5       GAS                     NORMAL      IDEAL GAS     
      6       BCC_A2                  NORMAL      PURE SUBSTANCE
      7       DIAMOND_A4              NORMAL      PURE SUBSTANCE

The entries under PHASE can appear much like a SUBSTANCE list. This arises as follows. Many pure substances are stored on the database without explicit phase names - for example zinc oxide may be stored within the database as a combined data set for the crystal and liquid phases rather than as ZnO<wurtzite> and ZnO<liquid> separately. The program generates phase labels from the chemical formula, in this case ZnO. Thus, all condensed substances without explicit labels must form separate phases. This does not apply to gases or aqueous solutions, which all belong to the same phase, irrespective of the secondary phase label, which is used to identify isomers.

On the other hand all substances that have the same phase label are deemed to be constituents of a solution phase. Thus if two non-gaseous substances, possibly from different databases, have the same phase name they will be assigned to a solution phase. If binary solution data are missing, unless the MTDATA configuration variable MISSING_DATA=CONTINUE (see Section 4.7) an entry will be placed in the output datafile reporting the lack of solution data: Removal of this entry will cause the phase to be treated as ideal.

As with SUBSTANCE each phase can be CLASSIFY'd as NORMAL (present) or ABSENT. Note that if a phase is CLASSIFY'd as ABSENT, the corresponding substances as displayed under LIST SUBSTANCES are not flagged as ABSENT. Nevertheless, when SAVEd, these substances are deleted from the SUBSTANCES list. The information in the column headed model is accurate only after the SAVE command has been issued.

ALL Entry of ALL is equivalent to entry of COMPONENTS SUBSTANCES ELEMENTS PHASES. All are listed.

General comments:

The information provided by the LIST command is important for use in CLASSIFY where both SUBSTANCE and PHASE may be referred to by the number appearing in the relevant list. Although parameter values can be given in any order, the output from LIST is in a fixed sequence: elements, components, phases, unaries/substances.


Updated 24 June 2010