As a tutorial, here we calculate Fe-O-S-Cr system under the conditions as follows. Note that MALT should be running and retrieve Fe-O-S-Cr system before the following operations.
In this tutorial, successive calculation for Cases are described. If the problem is focused on 1 point equilibrium calculation, however, Platform offers more primitive and easy operation. Anyway, step1 and step2 are always needed.

Number of cases	9 cases
Calculation Mode	Gibbs
Temperature	from 1200K to 2000K step 100K
Initial mole conditions	Fe : 9 SO2 : 10 Cr : 1

step 1	Execute gem
step 2	Get Thermodynamic data from MALT
step 3	Set Number of cases
step 4	Set Calculation Mode
step 5	Set Temperature --> Available temperature range of thermodynamic data
step 6	Set Pressure(atm) / Volume(litre)
step 7	Set Initial Mol --> To oust a compound from the calculation
step 8	Calculate
step 9	Chart output data
step 10	Save the Project

step 1

Execute gem

There are 4 ways of executing gem. One is the usual way such as double clicking of gem.exe in file explorer. gem will appear as Fig.1.

The second way is from MALT menu > tools > gem. In this case, gem will appear as Fig.2 with the compound system currently retrieved by MALT (See step2).

The third way is the one using Windows Start Menu > Execute with file name. Here you can specify the filename 'gem.exe' as in the one of the followings.

• Just 'gem.exe', this brings the same execution of gem as the first way.
  
• With the switch meaning MALT Direct, 'gem.exe /md', this has the same effect as the second way.
  
• With the project file name, which is already saved as a project file (*.gem), 'gem.exe ProjectName.gem' See Open Project Menu. Alternatively, If you set the linkage between gem project file (*.gem) and gem.exe file under Windows, you can perform this by double clicking the project file in file explorer.
  

The fourth way is to use batch file (*.bat). This enables user to process consecutive projects and to output text files for tables accordingly. For details, see Advanced Usage.

Fig.1  : Starting display of gem

step 2

Get Thermodynamic data from MALT

Click Menu: File > Malt Direct or Malt Direct Button in toolbar.

This step is needed only when you choose the first way to execute gem in step1. gem will get the compound system currently retrieved by MALT.
Fig.2 is the display after this command, and alphabets indicated upon the figure will be used in the following explanations.

Fig.2  : After getting thermodynamic data.

step 3

Set Number of cases

Simply input '9' as the number of cases and enter key into the edit box located in the middle of tool bar (A in Fig.2).
This operation can be made anytime, but you must fill the data in all cases after increasing the number of cases.
---Alternatively, you can use NT command from CommandBox.

step 4

Set Calculation Mode

Left click on the 3rd row, leftist column of Cases (B in Fig.2). The letter there is G (means Gibbs mode) or A (means Helmholtz mode), and is toggled by the click.
---Alternatively, you can use G or A command from CommandBox.

step 5

Set Temperature (K)

You can simply input the values into appropriate cells directly. But if the temperature change is regular such that it is expressed as initial value and step value, then left click on the 2nd row, the 2nd column where 'Temperature(K)' is shown. (C in Fig.2)
A dialog box called Promtform will appear, then input the initial value(2200), comma(,), step value(100), that is, '2200,100' (Fig.3) and click OK button (or enter key). All cells in Temperature row will be filled in accordance with the initial, step values you set. Step value can be specified two ways, one is usual number as increment, other is the number with the first letter @ as multiplier. See example and alternative T command in CommandBox.

Fig.3  : Promptform used for setting Temperature, Pressure/Volume and initial mols.

Fig.3A  : Available temperature range of thermodynamic data

Each compound has its available temperature range of the thermodynamic data. If the specified temperature for a calculation is beyond the temperature range of a compound, the data is regarded as not available and the compound will be out of consideration. You can extrapolate the data along the temperature and have the compound involved in the calculation, but should be careful. Especially some aqueous species have only 298.15K data, special attention is required. Such extrapolation for aqueous species and non-aqueous species can be controlled in Tools > Settings. Also you can control the extrapolation for each compound in Platform.

step 6

Set Pressure(atm)/Volume(litre)

In Gibbs mode, you should set pressure in atm, in Helmholtz mode, you should set volume in litre. The way to set them is the same as Set Temperature (Left-click on D in Fig.2 ) . In this case, input '1,0' in Promptform for pressure.
---Alternatively, you can use P or V command from CommandBox.

step 7

Set Initial Mol (mol)

The way to set them is the same as Set Temperature . Click the cell holding Compound Name to show the Promptform.
The cell on which you do not set any value is regarded as value 0.
---Alternatively, you can use N1, N2 command from CommandBox.
---See Advanced Usage for more sophisticated settings.

****** Important Caution ******
Let the value of initial mol is m, then m should be in the range of:
0.001<m<1000
This restriction comes from numerical dynamic range of calculation, and gem ignore the value less than 1E-8.
For simple reaction, m should be in the order of 1. If the system includes atmospheric gas, however, you can set larger value than above for the gas (but do not set value larger than 1E+10). To set values so that moving quantities would be in the above range is right choice.

*** *** *** *** *** *** *** *** *** ***

******To oust a compound from the calculation******
When you want to oust a compound from the calculation, fill in "out" (case insensitive) in the cell of the Cases sheet, or fill in "out" in the prompt form. You can do copy & paste too. The calculation result cell will show "out" in Results sheet and Activity sheet.

step 8

Calculate

Run or Run 1 Case can be used to calculate all cases or specified one case respectively. If you want to cancel the calculation already started, Stop Engine. When you execute Run 1 Case then you can see Sorted Output for the case.

step 9

Chart output data

You can select the compounds to be charted simply by click on the leftist cell of the compound (E in Fig.2) in Cases, Results or Activities respectively. Color dialog box will appear (Fig.4), then choose color in which the line of the compound will be drawn. Click again the cell to cancel the selection. Graph menu will show line chart for selected compound's mols or activities. See Charting and Printing.

Fig.4  : Specify color for the line of the compound to be drawn in the Graph.

step 10

Save the Project

After these operations, you can save the contents of Cases and the contents of thermodynamic data of this system for restarting from the same conditions later.
There are two files to be saved by Save Project , one is *.mcd file which contains thermodynamic data for this system, and *.gem> file which contains Cases contents and some parameters including mcd file name. Later, Open Project *.gem file, then you will find the same environment to resume the consideration. ---Note that gem always needs MALT running whether there is mcd file or not.