Perple_X BUILD prompts


NO is the default (blank) answer to all Y/N prompts


In this context, "default" is what Perple_X assumes if the user simply presses the enter key in response to a prompt.

Enter a name for this project (the name will be used as the root for all output file names) [default = my_project]:


Project names should not include blanks or "." characters, but they may include directory information. The project name can be up to 100 characters long, but because output files are named using project name plus various suffixes (e.g., .dat, .plt, .prt, .arf, .tof, .tab) it is unwise to specify names that are longer than 93 characters.


The file created by BUILD is named my_project.dat and specifies the calculation desired by the user. Once created, the file can be edited to modify the calculation.

Enter thermodynamic data file name, left justified, [default = hp02ver.dat]:


The thermodynamic data file contains the basic thermodynamic data for all stoichiometric phases and/or species. Typically the files are named XXNNver.dat where XX indicates the authorship or source and NN is the year of the last revision. Sources and brief descriptions of commonly used  files are at thermodynamic_data_files.

Enter the computational option file name, left justified, [default = perplex_option.dat]:

Many computational (run-time) options used by Perple_X are controlled via the computational option file. This file is normally named perplex_option.dat. Provision is made here to specify an alternative name because it sometimes desirable to have customized versions for specific purposes (e.g., high resolution or solvus calculations).

The current data base components are:
 NA2O  MGO   AL2O3 SIO2   K2O   CAO  ...
Transform them (Y/N)?


This option would permit the user to redefine the data base components, e.g., to create Fe2O3 from the components FeO and O2.


Component transformations in BUILD are tedious, so if you are going to do many calculations with transformed components the program CTRANSF can be used to create a thermodynamic data file with transformed components. (CTRANSF is demonstrated in chapter 6 of the, otherwise out-of-date, Perple_X Tutorial).

Calculations with a saturated phase (Y/N)?

The phase is: FLUID

Its compositional variable is: Y(CO2), X(O), etc.


Select the independent saturated phase components:

 H2O   CO2

Enter names, left justified, 1 per line, [cr] to finish:


For C-O-H fluids it is only necessary to select volatile species present in the solids of interest. If the species listed here are H2O and CO2, then to constrain O2 chemical potential to be consistent with C-O-H fluid speciation treat O2 as a saturated component. Refer to chapter 6 of the Perple_X Tutorial for details.


Saturated phase components are components whose chemical potentials are determined by the assumed stability of a phase, usually a fluid, containing these components.


Typically this option is selected to compute phase relations as a function of the composition of the saturated phase, as in P-T-X(CO2) diagrams that show phase relations as a function of the composition of a fluid that is assumed to be stable.


There are two important implications to specifying a saturated phase: 1) it implies that the phase components are always present in sufficient quantity to saturate the system in the phase; 2) it implies that the specified phase is always stable. Thus, if you are interested in a system with excess H2O, but the physical conditions of the system may be those at which ice is stable you should specify H2O as a saturated component and not as saturated phase. Similarly, if water may not be always present as a pure phase you should specify H2O as a thermodynamic component.


NOTE: Because specification of H2O as a saturated phase component causes Perple_X to exclude any phases with the H2O composition that are not named "H2O", H2O should not be specified as a saturated phase component in calculations involving a hydrous silicate melt if, as is commonly the case, the melt model involves a water endmember that is not named "H2O".

Calculations with saturated components (Y/N)?


**warning ver015** if you select > 1 saturated component, then the order you enter the components determines the saturation hierarchy and may affect your results (see Connolly 1990).


Saturated components are components whose chemical potentials are determined by the assumed stability of pure phase(s) or solutions consisting entirely of  saturated-phase and saturated components. E.g., a system that contains so much silica that a silica polymorph (e.g., quartz or coesite) is stable at all conditions of interest can be specified here by selecting SIO2 as a saturated component.


If more than one saturated component is specified Perple_X applies the constraints sequentially, e.g., if AL2O3 and SIO2 are specified as the first and second components, then the excess phases might be corundum + andalusite, if the order is reversed then at the same condition the stable phases would be quartz + andalusite. This sequence is referred to as the saturation hierarchy, see Tutorial Chap 3 for further discussion.  

Use chemical potentials, activities or fugacities as independent variables (Y/N)?


Select < 3 mobile components from the set:
 NA2O  MGO   AL2O3 SIO2   K2O   CAO  ...
Enter names, left justified, 1 per line, <cr> to finish:


If you answer yes to the first prompt you are prompted for the mobile components, i.e., the components whose chemical potentials, activities or fugacities are to be specified as independent variables.

Select thermodynamic components from the set:
 NA2O  MGO   AL2O3 K2O   CAO   TIO2  MNO   FEO   ...

Enter names, left justified, 1 per line, <cr> to finish:


Thermodynamic components are components whose chemical potentials are the dependent (implicit) variables of a phase diagram calculation. Phase diagram calculations require the specification of at least one thermodynamic component.

**warning ver016** you are going to treat a saturated (fluid) phase component as a thermodynamic component, this may not be what you want to do.


This warning is given because H2O and CO2 are usually treated as saturated phase components.

Select fluid equation of state:


 0 - X(CO2) Modified Redlich-Kwong (MRK/DeSantis/Holloway) 
 1 - X(CO2) Kerrick & Jacobs 1981 (HSMRK) 
 2 - X(CO2) Hybrid MRK/HSMRK 
 3 - X(CO2) Saxena & Fei 1987 pseudo-virial expansion 
 4 - Bottinga & Richet 1981 (CO2 RK) 
 5 - X(CO2) Holland & Powell 1991, 1998 (CORK) 
 6 - X(CO2) Hybrid Haar et al 1979/CORK (TRKMRK) 
 7 - f(O2/CO2)-f(S2) Graphite buffered COHS MRK fluid 
 8 - f(O2/CO2)-f(S2) Graphite buffered COHS hybrid-EoS fluid 
 9 - Max X(H2O) GCOH fluid Cesare & Connolly 1993 
10 - X(O) GCOH-fluid hybrid-EoS Connolly & Cesare 1993 
11 - X(O) GCOH-fluid MRK Connolly & Cesare 1993 
12 - X(O)-f(S2) GCOHS-fluid hybrid-EoS Connolly & Cesare 1993 
13 - X(H2) H2-H2O hybrid-EoS
14 - X(CO2) Pitzer & Sterner 1994; Holland & Powell mixing 2003
15 - X(H2) low T H2-H2O hybrid-EoS 
16 - X(O) H-O HSMRK/MRK hybrid-EoS 
17 - X(O) H-O-S HSMRK/MRK hybrid-EoS 
18 - X(CO2) Delany/HSMRK/MRK hybrid-EoS, for P > 10 kb 
19 - X(O)-X(S) COHS hybrid-EoS Connolly & Cesare 1993 
20 - X(O)-X(C) COHS hybrid-EoS Connolly & Cesare 1993 
21 - X(CO2) Halbach & Chatterjee 1982, P > 10 kb, hybrid-Eos 
22 - X(CO2) DHCORK, hybrid-Eos 
23 - Toop-Samis Silicate Melt 
24 - f(O2/CO2)-N/C Graphite saturated COHN MRK fluid
25 - H2O-CO2-NaCl Aranovich and Haefner 2004


Some of the equations of state listed are for specialized applications or for a restricted range of conditions. CORK (choice 5) and Pitzer & Sterner (1994, choice 14) are good general purpose equations of state that extrapolate well to extreme pressure.


A common mistake in calculations using these equations of state is that users specify a pressure-temperature conditions at which these equations are numerically unstable. As a general rule these equations should not be used at pressure-temperature conditions much lower than the water critical point. They should never be used at zero pressure.

Compute f(H2) & f(O2) as the dependent fugacities (do not unless you project through carbon) (Y/N)?


Answer yes this prompt to describe the fluid with components H2 and O2 instead of H2O and CO2 (Tutorial Chap 6 and Connolly 1995)

The data base has P(bar) and T(K) as default independent potentials. Make one dependent on the other, e.g., as along a geothermal gradient (y/n)?


See perplex_tx_pseudosection for an example of a calculation made along a geothermal gradient.

Specify computational mode:

     1 - Unconstrained minimization
     2 - Constrained minimization on a 2d grid [default]
     3 - Constrained minimization on a 1d grid
     4 - Output pseudocompound data
     5 - Phase fractionation calculations

Use unconstrained minimization for Schreinemakers projections or phase diagrams with > 2 independent variables. Use constrained minimization for phase diagrams or phase diagram sections with < 3 independent variables.


In unconstrained minimization, only thermodynamic potentials (pressure, temperature, chemical potentials) or directly related properties such as the composition of a saturated phase can be chosen as explicit variables. A diagram with no explicit potential variables is a composition diagram, any other diagram is technically a mixed-variable diagram (potentials and compositions); however in Perple_X, diagrams with only one explicit independent potential variable are designated mixed-variable diagrams, whereas as diagrams with two explicit independent potential variables are designated  Schreinemakers-type diagrams if the thermodynamic components are unconstrained or as isochemical phase diagram sections (aka pseudosections) if the amounts of the thermodynamic components are specified. Refer to the, out-of-date, Perple_X tutorial and examples files for more information about composition and Schreinemakers diagrams.


In constrained minimization (Connolly 2005) phase relations are mapped by free energy minimization on a 1- or 2-dimensional grid, whereby the stable assemblage determined at each grid point is assumed to be stable over the area associated with the grid point. For more information about mode [2] calculations refer to the seismic velocity, tx_pseudosection, and adiabatic_crystallization tutorials, for mode [3] calculations see Example 23.


For a tutorial on mode [5] calculations refer to the phase_fractionation tutorial.

For gridded minimization:


Select x-axis variable:
     1 - P(bars)
     2 - T(K)
     3 - Composition X(C1)* (user defined)
*X(C1) can not be selected as the y-axis variable


In gridded minimization calculations it is possible to construct phase diagram sections as a function of any arbitrarily defined composition (variable X(C1) in this prompt), for example it is possible to make a phase diagram section that shows how the phase relations of a pelitic system would change as its composition is varied by the addition water or a basaltic component. If the user selects X(C1) as a variable, the meaning of the compositional variable is defined in response to later prompts. An example of this type of calculation is in the tx_pseudosection tutorial.

Enter weight amounts of the components:
 SIO2  TIO2  AL2O3 FEO   MGO   CAO   NA2O  K2O   H2O   CO2
for the bulk composition of interest:




Enter molar amounts of the components:
 SIO2  TIO2  AL2O3 FEO   MGO   CAO   NA2O  K2O   H2O   CO2
for the bulk composition of interest:


VERTEX requires the amounts of the components, the units used and total value of the components have no fundamental importance, but define the molar unit for the system. For numerical reasons the weight or molar quantities specified here should not differ by many orders of magnitude from those typical of the phases in the thermodynamic database. Rational molar amounts (1/2, 1, 0, etc.) should be avoided because this is likely to lead a situation in which the composition lies on a tie-line, in such cases there is no unique solution to the phase equilibrium problem.

Output a print file (Y/N)?


If the user answers yes to this prompt VERTEX and MEEMUM generate a file named my_project.prt.


For unconstrained minimization calculations, particularly mixed-variable diagrams and Schreinemakers projections, the print file contains a summary of the computed phase equilibria. The keywords reaction_format, dependent_potentials, reaction_list, and short_print_file specified in perplex_option.dat control the data output to the print file.


The print file output is not useful for unconstrained minimization calculations except: 1) if MEEMUM is used, in which case the print file echoes the console output; or 2) an explicit list of the phases considered in the calculation is desired. 

Exclude endmember phases (Y/N)?

For inexperienced users it is best to begin by including all possible endmember phases (i.e., stoichiometric or pure phases and stoichiometric chemical potential buffers). This allows the user to identify flaws in her perception of what the stable phases should be and/or problems in the thermodynamic data.


The endmember phases are identified by abbreviated names, in general these abbreviations are defined in the header section of the thermodynamic data file, in a few cases separate lists of endmember abbreviations are available (perplex_citation).

Include solution phases (Y/N)?


By default all endmember phases and no solution phases (i.e., non-stoichiometric phases) are included in calculations.

Enter solution model file name [default = solution_model.dat]:


The "solution model file" defines the parameters for the solution phases to be considered in a calculation; these parameters not only specify thermodynamic properties, but also the "subdivision scheme" used to generate pseudocompounds.


The current/default solution model file is named solution_model.dat; older versions of this file are named solut_##.dat where ## indicates the year of the last revision. Certain thermodynamic data bases require specific solution model files, e.g., stx11ver.dat requires stx11_solution_model.dat.

Select phases from the following list, enter 1 per line, press <enter> to finish:


The art of using Perple_X is to choose the solution models appropriate for a particular problem, the solution model glossary and the commentary within the solution model file itself may be helpful in this regard.


A common error, with potentially catastrophic consequences, is that users select several solution models representing the same real solution. There are situations where this practice makes sense, but if it's not clear to you when this is true, then chances are you shouldn't be doing it.