Entering Many Equilibria as a Table

When one thermodynamic variable (e.g. heat capacity) has been measured as a function of another (e.g. temperature), then experimental data is often presented as a table. By using the table_head, table_values and table_END commands, you can enter such experimental information into the POP file in the form of a table. These three commands should always be used together and must be entered in the right order. See TABLE_HEAD, TABLE_VALUES and TABLE_END.

The TABLE_HEAD command is followed by a number. This number identifies the table as a whole, but also uniquely identifies the first equilibrium that is included in the table. This numeric identifier is incremented by one for each additional equilibrium in the table. Each row in the table represents one equilibrium. Thus, the equilibrium defined by the first row in the table above (on the line immediately below TABLE_VALUE) is uniquely identified with the number 1, the equilibrium defined by the second row by number 2, and so on until the last equilibrium on the sixth row, which is identified by the number 6.

Since the unique identifiers of the equilibria in the table are automatically generated from the unique numerical identifier that you give to the table, the unique numerical identifier that is normally given to the CREATE_NEW_EQUILIBRIUM command is replaced by two at signs (@@).

At least one of the equilibria conditions specified with the SET_CONDITION command must be a condition whose value is set by the numbers in one of the table columns. To assign the numbers in a column to a condition, use the syntax SET_CONDITION <condition>=@<column number>. For instance, in the example above, the mole fraction of X(ALO3/2) is for each equilibrium given by the number in the first column of the table.

At least one of the measured variables that are entered with the experiment command must be a variable whose value is set by the numbers in a table column. To assign the numbers in a column to a measured variable, use the syntax EXPERIMENT <variable>=@<column number>. In the example above, the measured temperature for each equilibrium is given by the number in the second table column.

The actual table should be entered between table_values and table_end. Separate the columns with tabs or any number of spaces. The columns do not have to contain numbers, but can also contain other types of values, such as phase names for example. If a column contains text with spaces or special characters, then the text must be surrounded by double quotes (“ABC DEF&ghi”, for example). The table may have columns that are not used, but each row must have exactly the same number of columns.

The following block of commands exemplifies how a table can be entered into a POP file:

TABLE_HEAD 1

CREATE_NEW_EQUILIBRIUM @@ 1

CHANGE_STATUS PHASE TETR=FIX 0

CHANGE_STATUS PHASE ION=ENT 1

SET_CONDITION P=101325 N=1 ACR(O2,GAS)=.21 X(ALO3/2)=@1

EXPERIMENT T=@2:5

TABLE_VALUE

0.4608 2476

0.5714 2380

0.6682 2276

0.7496 2176

0.5038 2426

0.6313 2249

TABLE_END