The Calc Ptrap tab is for calculating the entrapment pressure of the inclusion when you know the final pressure in the inclusion at another P and T.
Enter the final conditions in the boxes:
- Pend(host) is the external pressure on the host at the final conditions. Set this to 0.0 if you measured the inclusion pressure when the host is at room conditions.
- Tend is the temperature of the host and the inclusion at the final conditions.
- Pinc is the measured pressure in the inclusion at the final conditions.
The entrapment pressure cannot be determined uniquely with the isotropic elasticity model for host-inclusion systems. It can only be calculated if the entrapment temperature is known. Set a range of entrapment temperatures from Tmin to Tmax in steps of Tstep.
Press the Calculate button to get the results. Warning: the results are only displayed in the information panel when you press this button!

The information panel shows:
- The final conditions.
- The pressure change in the inclusion due to the mutual relaxation, calculated with an iterative solution to the relaxation problem based on the elastic hollow sphere solution (Angel et al., 2017). Important: if you have an EoS for the host without a value for the shear modulus, then the relaxation will be calculated as zero.
- The thermodynamic pressure in the inclusion (Pthermo). This is the pressure calculated as the inclusion volume subjected to the volume change of the host, without mutual elastic relaxation.
- The pressure of the entrapment isomeke at the final temperature (Pfoot)
- A list of entrapment pressures for the temperature range and steps selected. These are points on the entrapment isomeke.
If the program is run in expert mode, you will also see the intermediate pressures calculated with several different models for relaxation from the literature. The entrapment isomeke is always reported for the exact model (#5).
Pthermo input
You can also calculate entrapment pressures from estimates of Pthermo instead of Ptrap. This allows you to use inclusion pressures unrelaxed by calculations in external programs, for example if you have a FE model of the inclusion from which you have calculated the relaxation.
To input a value of Pthermo instead of Pinc, just untick the box next to the 'Pinc' input, and you will see the label change to 'Pthermo'. Input 'Pthermo' and hit the 'Calculate' button:

Read Pinc or Pthermo from file
You can also calculate entrapment isomekes from a series of P (or Pthermo) values in a text file:
- Create a text file with the Pinc (or Pthermo) values, one on each line.
- Set Pend, Tend, and the tick box on the GUI to indicate Pthermo or Pinc
- Set the temperature range and step for the calculation of the entrapment isomekes on the GUI
- Then press the button 'Read Pinc or Pthermo from file', open the file, and the isomekes will be calculated for each value of pressure in the file.
- Note: a better-formatted output is written to the log file, if it is open.