Bulk Composition entry and Liquid Composition Display

Phase Proportions and Thermodynamic Properties

Status Display

The user may find the following items reported to the status display panel useful in interpreting other results on the MELTS interface:

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`Constraint Change: System temperature.`Each time the

**temperature**or some other constraint parameter (see**T,P...**entry of the Intensive Variables menu) changes during a model calculation, the change is announced in this panel. `...Checking saturation state of potential solids.`One of the most time-consuming phases of any calculation is

**evaluating the saturation states of the solid phases**as the temperature, pressure and liquid composition changes.**Before**entering this phase of the calculation, the above message is displayed. Saturation states are always evaluated before an attempt is made to determine the equilibrium state of the system.`...Projecting equality constraints.``...Minimizing the thermodynamic potential.`Both of these messages announce the

**initiation**of an attempt to**calculate the equilibrium state**of the system.`...-->Solving quadratic minimization Iter: 1.`The

**minimization of the thermodynamic potential**is performed in a series of*quadratic*approximations. Each approximation generates a solution and a residual vector.`...-->rNorm = 0.0316353, sNorm = 0.310069`The

**norm**(or*length*) of these vectors is given by`sNorm`and`rNorm`respectively. When the series of quadratic approximations have found the minimum of the thermodynamic potential,`rNorm`should be zero.`...-->Linear search: Min = -1.63844e+06, step = 0.923328``...-->Linear search: Min = -1.63844e+06, step = 1`A quadratic minimization attempt is following by a

**linear search**out along the quadratic search direction. This linear search attempts to locate the function minimum. If things are going well, the**steplength**along the quadratic search direction (`step`) should be near unity.`Min`gives the value of the thermodynamic potential being minimized.`...-->Solving quadratic minimization Iter: 6.``...-->rNorm = 1.52606e-13, sNorm = 0.311589``...Checking saturation state of potential solids.`As the function minimum (i.e. equilibrium) is reached,

`rNorm`decreases**below machine precision**and the quadratic approximation sequence is terminated.*Saturation states are checked once again to make sure some other phase has not appear ed on the liquidus during the course of minimizing the potential.*`...Quadratic convergence failure. Aborting.`If more than 100 quadratic steps are executed and

`rNorm`has not decreased sufficiently to toggle convergence, you will see the above message and this dialog box will appear. In this event, perturb the system a bit by changing T, P or bulk composition slightly and start the calculation again using the**Execute/Halt**entry on the Commands menu.`<> Stable liquid solid assemblage achieved.``Current state of the system recorded in file MELTS.OUT.`These messages indicate that the compositions and proportions of

**liquid and solid phases**displayed on the MELTS interface represent a stable or**equilibrium assemblage**.