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alphaMELTS 1.9 is available at the download and information site.
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#61
Windows / Re: Can't spawn "cmd.exe"
Last post by Paula - February 01, 2023, 03:22:08 PM
Hi,

How are you starting run_alphamelts.command? If alphaMELTS is installed correctly, you shouldn't need to put the full path to run_alphamelts.command. You should be able to navigate to where the input files are in cmd.exe and then start alphaMELTS by typing "run_alphamelts.command -f PMPLP_env.txt -o output" etc.

I'm not that surprised it fails when called like that, though I don't understand what's changed since it was working.

Assuming you took the default settings when you ran install.command, the links will be in C:\Users\admin\Documents\bin - is this folder in the Path (type "echo %PATH%" in cmd.exe)? If it is not then you will get an error, as it will be looking for alphamelts(.bat) in the C:\Users\admin\Documents\alphamelts_1-9 folder. But again it won't be exactly the same error as you are getting.

I am at IAVCEI and only have access to Windows 11 (with Malwarebytes) and have not been able to reproduce what you see. As mentioned  before I would try running install.command again, the way you are supposed to the first time (i.e. right-click, open with...). If it still doesn't work then try copying cmd.exe into C:\Users\admin\Documents\bin - it's not an ideal solution but it might work.

Paula
#62
Windows / Re: Can't spawn "cmd.exe"
Last post by joaotumenas - January 23, 2023, 09:33:37 AM
Hello, Paula.

Sorry for taking so long to reply

I am admin on the machine. I installed perl using the automatic installer file available from the website download, without using Anaconda, ActivePerl or something else.

However I have Malwarebytes installed on my machine and the problem doesn't solved itself with normal updates.

Can you help me with this problem, please?


The message of error is:

"C:\Users\admin\Documents>C:\Users\admin\Documents\alphamelts_1-9\run_alphamelts.command -f C:\Users\admin\Documents\alphamelts_1-9\Joao\PMPLP_env.txt -p C:\Users\admin\Documents\alphamelts_1-9\output
ALPHAMELTS_DO_TRACE true
ALPHAMELTS_DO_TRACE_H2O true
ALPHAMELTS_CELSIUS_OUTPUT true
ALPHAMELTS_VERSION MELTS
ALPHAMELTS_DELTAP 0
ALPHAMELTS_MINT +850
ALPHAMELTS_MAXP +3000
ALPHAMELTS_MAXT +1500
ALPHAMELTS_MODE isobaric
ALPHAMELTS_MINP +3000
ALPHAMELTS_MINF 0.05
ALPHAMELTS_DELTAT -10


Can't spawn "cmd.exe": No such file or directory at C:\Users\admin\Documents\alphamelts_1-9\run_alphamelts.command line 447.
RUN_ALPHAMELTS.COMMAND WARNING: alphamelts may have crashed!


RUN_ALPHAMELTS.COMMAND WARNING: Cannot find output file "Phase_main_tbl.txt" (No such file or directory)
Please check that alphamelts ran properly."
#63
Hi Richard,

First, this composition is illegal as a superliquidus state in MELTS, because it doesn't have enough SiO2 to plot between the liquid end members that have been adopted to describe the silicate liquid phase.

Let me explain: MELTS represents the liquid as a solution among mineral-like molecules. The molecules that were chosen to represent the 9 oxides you are using are Si4O8, TiO2, Al4O6, MgCr2O4, MnSi0.5O2, Mg2SiO4, NiSi0.5O2, CaSiO3, Na2SiO3, KAlSiO4. To make a legal liquid, the number of each of this molecules must be non-negative. But if you convert your weight percents to oxide mole fractions, you'll see right away that SiO2 < (MgO/2) + CaO ... that is, you don't have enough SiO2 to make all the forsterite molecules needed to take up the MgO and the wollastonite molecules needed to take up the CaO. So the error you're getting is entirely appropriate.

Second, did you mean to have absolutely no iron in the system, or did you leave it out? At IW-4.93, maybe there is no FeO left ... I'm just checking. In any case, imposing an fO2 has no meaning in MELTS is there is no Fe in the system ... the only way that it knows how to measure or buffer fO2 is by via the Fe3+/Fe2+ ratio.

In principle, there may be a workaround if you don't try to model the near-liquidus region. A subsolidus initial guess may exist from a state that contains forsterite plus periclase plus other minerals. Then you could work up from there. But the subsolidus initial routine built into alphaMELTS isn't general enough to handle that case. You'd have to use the MATLAB or Python interface to construct the initial guess.
#64
Hello,

I am working on a project investigating the crystallization of Mercury's magma ocean, and was hoping for some guidance on how to use MELTS to that end.  The issue that I am having is the extreme reducing conditions and odd composition of the magma. I have my starting composition based off of the Indarch meteorite (from Berthet et al. 2009) and was going to remove silicon from the composition at varying levels to simulate the Si being partitioned into the core. I am unable to run any calculations past finding the liquidus which is much lower temp than I would expect (around 678 C). When I attempt to execute I get a SiO2 has a negative mole fraction, and as I've looked through the forum I have not found a solution as of yet.

Any help would be greatly appreciated!

wt. %.

SiO2 - 38.67
MgO - 49.22
Al2O3 - 4.08
CaO - 2.68
Na2O - 2.84
K2O - 0.31
Cr203 - 1.32
MnO - 0.70
TiO2 - 0.17

Temp was 1800 C to 1400 C
Pressure was 2.5 GPa to 1.0 GPa
fO2 (IW) was -4.93 from computing the redox state.

The system crashes at any attempt to execute past finding the liquidus.

Thanks again for any help!

Cheers,
Richard Gwyn
gwynr@wwu.edu
#65
Melting processes / Re: How to set D for select el...
Last post by Yujian Wang - December 06, 2022, 06:53:39 PM
Thank you Paula. Problem solved.
#66
Melting processes / Re: How to set D for select el...
Last post by Paula - December 06, 2022, 08:40:53 AM
Hi,

It sounds like you need to set ALPHAMELTS_TRACE_INPUT_FILE to "default_trace_data.dat" so it reads in the file instead of using the built-in values.

Paula
#67
Melting processes / How to set D for select elemen...
Last post by Yujian Wang - December 06, 2022, 05:30:15 AM
Hello,

I am using alphaMELTS 1.9 to model variations of major and trace element during melt-rock interaction. I want to sent my own partition coefficients for selected elements between cpx and melt. I unset the ALPHAMELTS_TRACE_DEFAULT_DPTX and changed the values in "default_trace_data.dat". Unfortunately, it doesn't appear to work that way. AlphaMELTS executable seems still keeping the default values. Should I have to make a new trace_data file? But How can I read these in?
#68
It depends how you are calculating Cp for the Berman model. Are you taking the Cp expressions from Berman & Brown (1985)? There are a couple of sources of discrepancy:


  • For albite you need to accounting for Al-Si order / disorder. The approach used is described on page 498 of Berman (1988) and encoded in the albite.c file that is part of the MELTS source code.
  • Pure phases that include 2nd order transitions, such as the silica polymorphs, have slightly different Landau contributions to Cp in Berman (1988), as compared to Berman & Brown (1985). The correction is implied by, but not discussed in, Berman (1988), and is also not mentioned in the MELTS papers.
The solution properties of feldspar in MELTS are taken from Elkins and Grove, Ternary feldspar experiments and thermodynamic models, American Mineralogist 75, 544-559 and encoded in feldspar.c. The expressions from that give the Gibbs Free Energy of mixing (Gmix). The Cp of mixing is Cpmix = - T 2Gmix/∂T2

However, for feldspar and most of the other solution phases in MELTS models, the Cpmix term is zero. See the following and the code for more details:
If you want to view the MELTS source code you should sign up for GitLab (gitlab.com) and write to Mark Ghiorso (ghiorso@ofm-research.org) with your GitLab username to request access.
#69
Thank you very much for your response. I was also checking on the mineral phases' Cp, and I don't quite get the same results using Berman (1985) model, most probably because this model accounts for the end members solid solutions. How is it computed for, for example, a "plagioclase1" with a not end-member albite composition? Meaning that it is not pure NaAlSi3O8, but this is the predominant composition.

Thank you very much!
#70
Website issues, and Miscellaneous / Re: Correct application of fra...
Last post by Paula - November 22, 2022, 07:42:07 AM
Is this alphaMELTS 1.9 or 2?