NO is the default ([cr]) 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 name of computational option file to be created, < 100 characters, left justified [default = in]:
Perple_X file names may include directory information. The file designated here will be created by BUILD and describes the computation 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.
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 Perple_X program CTRANSF can be used to create a new thermodynamic data file with transformed components. (I think CTRANSF is demonstrated in the Tutorial).
Calculations with a saturated phase (Y/N)?
The phase is: FLUID
Its compositional variable is: Y(CO2), X(O), etc.
y
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 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.
Calculations with saturated components (Y/N)?
y
**warning ver015** if you select > 1 saturated component, then the order you enter the components determines the saturation hierarchy and may effect 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.
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)?
y
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 are to be specified as independent variables.
Diagrams calculated with chemical potentials can be converted to diagrams with fugacities or activities using the program MU_2_F (see perplex_example_6).
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 - EoS Birch & Feeblebop (1993)
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 (5) is a good general purpose EoS that extrapolates 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 certainly should not 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 [default]
2 - Constrained minimization on a grid
3 - Output pseudocompound data
4 - Phase fractionation calculations
Unconstrained optimization should be used for the calculation of composition,
mixed variable, and Schreinemakers diagrams, it may also be used for the
calculation of phase diagram sections for a fixed bulk composition. Gridded
minimization can be used to construct phase diagram sections for both fixed and
variable bulk composition. Gridded minimization is preferable for the recovery
of phase and bulk properties.
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 diagrams (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 as Schreinemakers-type diagrams if the thermodynamic components are unconstrained and as "pseudosections" if the amounts of the thermodynamic components are specified. Refer to the, albeit out-of-date, Perple_X tutorial and examples files for more information about composition and schreinemakers diagrams.
Both modes [1] and [2] can be used for pseudosection calculations. The default mode [1] (Connolly & Petrini 2002) essentially consists of tracing the edges of each field of a polygonalized pseudosection. The alternative mode [2] is gridded minimization (Connolly 2004?). In gridded minimization the polygonalized pseudosection is mapped from free energy minimizations done 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. Each mode has features that makes it preferable for certain problems. At least for preliminary calculations I prefer gridded minimization because it is simpler to use and can be run at low resolution to provide rough results quickly. See gridded minimization pros and cons for more complete discussion of advantages of gridded minimization and the grid parameter choices made here. For more information about mode [1] pseudosection calculations refer to the pseudosection tutorial, and to the seismic velocity, tx_pseudosection, and adiabatic_crystallization tutorials for mode [2] calculations.
For a tutorial on mode [4] 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.
Select grid refinement mode:
1 - Refine only true phase boundaries, compression off [default].
2 - Refine all phase boundaries, compression on.
3 - Refine all phase boundaries, compression off.
The foregoing prompt determines what features will be resolved at the highest level of resolution. True phase boundaries are phase diagram boundaries where a phase first appears or disappears. In Perple_X the pseudocompound model results in a second type of boundary which represents the conditions at which there is no change in the identities of the stable phases, but where the composition of a pseudocompound representing one of these phases changes (e.g., the composition of plagioclase changes from 10 to 20% albite component).
NOTE: the previous version of WERAMI allowed an additional mode (resolution of only true phase boundaries with compression) that has been disabled in the current version.
Mode 1 - In this mode true phase boundaries are resolved at the maximum resolution of the grid, but physical properties are resolved only at the lowest resolution of the grid. This mode may result in an artificially blocky variation of physical properties. This mode has the same efficiency as mode 1, but results in larger files. For most purposes I recommend using this mode.
Mode 2 - Use this mode to maximize the resolution of compositional variations within phase fields. In this model all features are resolved at the maximum resolution of the grid. Mode 3 calculations typically increase the amount of time required for a calculation by at least an order of magnitude.
Mode 3 - Use this mode to obtain the maximum accuracy consistent with the Perple_X pseudocompound algorithm. Compared to mode 3, this mode reduces the error associated with the numerical extrapolations used to estimate physical properties in WERAMI. This mode has the same computational efficiency as mode 3, but may generate very large data files.
To reduce the size of output files, if compression is turned on VERTEX discards data at grid points associated with any assemblage that has already been identified at a previous grid point. Physical properties such as density and seismic velocities are then estimated, in WERAMI and PSVDRAW, by extrapolation from the retained grid points assuming the first, and for some properties higher order derivatives, of the property of interest are constant within the relevant polygonal field. In some instances, particularly when a single polygonal field spans a large pressure or temperature interval, this means of estimation may lead to significant errors (such errors are usually manifest by irregular variation across what should be a continuous phase field). To minimize such complications, compression should be turned off in VERTEX so that physical properties are sampled and output at relatively regular intervals.
NOTE 1: WERAMI and PSVDRAW currently do not interpolate (WERAMI now allows interpolation as an option) compositional variables, therefore modes [2] or [4] should be used if physical properties are to be recovered from a diagram with one or mode compositional variables.
NOTE 2: the response to this prompt determines two variables specified in the computational option file. If you wish to set these by editing the file then the line (compression on):
1 JTEST, debug flag
should be changed to
3 JTEST, debug flag
in order to turn compression off, and the line (refine only true phase boundaries)
1 for gridded minimization grid refinement, 1 - true boundaries, 0 - all boundaries
should be changed to
0 for gridded minimization grid refinement, 1 - true boundaries, 0 - all boundaries
For more information on gridded minimization strategy and compression refer to the out-of-date gridded minimization page or Connolly (2004?).
The
resolution of the grid is determined by the
number of levels (JLEV) and the resolution at the lowest level in the X- and
Y-directions (ILOW and JLOW, respectively), such that the maximum resolution is
equivalent to that obtained on a single level grid with 1+(ILOW-1)*2^(JLEV-1)
nodes in the X-direction and 1+(JLOW-1)*2^(JLEV-1) nodes in the Y-direction. To
force VERTEX to use a single level grid, set JLEV=1.
Enter the number of nodes (ILOW) in the X-direction for the lowest resolution grid (0<ILOW<2048) [default = 40]:
25
Enter the number of nodes (JLOW) in the Y-direction for the lowest resolution grid (1<JLOW<2048) [default = 40]:
25
ILOW and JLOW are the minimum number of regularly spaced nodes along the X- and Y- axes. For grid refinement mode 2 this defines the resolution at which physical properties will be sampled; in this mode, low values of ILOW and JLOW may result in rough property variation plots. More generally, the danger of using the low values for ILOW and JLOW is that a small phase field that protrudes into a larger phase field will not be identified if the protrusion occurs between two nodes of the low resolution grid at which the larger field is stable. There is no simple rule for the best choices for ILOW and JLOW as they depend on the scale of the diagram and the heterogeneity of its phase fields. I generally use values between 10 and 50.
Enter the number of levels (JLEV) for the grid (0<JLEV<10) [default = 4]:
The value specified here determines the highest resolution of the grid, i.e. (Xmax – Xmin)/[1+(ILOW – 1)*2(JLEV-1)] and (Ymax – Ymin)/[1+(JLOW – 1)*2(JLEV-1)]. Features that change between 2 grid points at the lowest resolution of the grid are resolved at this level of resolution. For grid refinement modes 1 and 2 the computational cost of higher levels is usually minor.
Enter weight amounts of the components:
SIO2 TIO2 AL2O3 FEO MGO CAO NA2O K2O H2O CO2
for the bulk composition of interest:
or
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.
Enter the plot file name, < 100 characters, left justified [default = pl]:
The name entered here forms the root for various other files generated by subsequent programs.
Exclude phases (Y/N)?
It is simplest to begin by including all possible end-member phases. This allows the user to identify flaws in her perception of what the stable phases should be and/or problems in the thermodynamic data. .
Enter solution model file name [default = newest_format_solut.dat] left justified, <100 characters:
The "solution model file" defines the parameters for the solution phases to be considered in the calculation; these parameters not only specify thermodynamic properties, but also the compositional range and resolution for each solution, i.e., the "subdivision scheme" used by VERTEX to generate pseudocompounds. In order to use Perple_X effectively it is essential to learn how to modify and refine the subdivision schemes specified in the solution model file (for an on-line example see p-t-x pseudosection tutorial, also see chapters 4 and 5 of the Tutorial and the Perple_X technical documentation for more information on subdivision schemes).
Currently, the only up-to-date solution model file at this web site is "newest_format_solut.dat", the subdivision schemes specified in this file are reasonable for the calculation of pseudosections and composition diagrams, but the resolution is too high and should be reduced for most phase diagram projection calculations (Schreinemakers-type diagrams).
Select phases from the following list, enter 1 per line, left justified, [cr] to finish:
The "art" of using Perple_X is in the choice of solution models, the solution model glossary and the commentary within the solution model file itself should be helpful in this regard.
For phases that exhibit immiscibility there are frequently two or more "solutions" that represent different compositional ranges of the same true phase, e.g., Pl, AbPl and AnPl all represent Ca-Na plagoioclase. The reason for this is that in most calculations Perple_X does not test whether coexisting pseudocompounds of the same solution are separated by a miscibility gap. Thus if a single model is used to represent the entire range of plagioclase (i.e., Pl), Perple_X will interpret coexisting albitic (AbPl) and anorthitic (AnPl) plagioclase as being a single phase (See Tutorial Chapters 4 and 5 or Connolly 1990, Connolly & Kerrick 1987, Connolly & Trommsdorff 1991).
A common error, with potentially catastrophic consequences, is that users select both the solution models for the complete compositional range and for the restricted ranges. This causes problems because it has the potential to create a situation in which two or more pseudocompounds have identical properties and therefore Perple_X cannot decide which one is stable. Another bad practice is that users select several different solution models (e.g., Mu and Pheng(HP), both models for potassic mica) representing the same solution. There are situations where this practice makes sense, but if you can't see that for yourself, then the chances are you shouldn't be doing it.