OpenCalphad

https://github.com/sundmanbo/opencalphad
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OpenCalphad is a free thermodynamic software for calculating multicomponent equilibria, property and...
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### Example Equilibrium Condition in OC

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Demonstrates how to specify complex equilibrium conditions in the OpenCalphad command line, such as defining a minimum of a liquidus line or a second-order transition.

```text
x(liq,cr)-x(bcc,cr)=0
```

```text
y(bcc-B2,Al)-y(bcc-B2,Al#2)=0.01
```

--------------------------------

### GET /list/short

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Provides a concise summary of elements, species, phases, or models based on the selected option.

```APIDOC
## GET /list/short

### Description
Lists essential data in a short format based on the provided option.

### Method
GET

### Endpoint
/list/short

### Parameters
#### Query Parameters
- **option** (string) - Required - Options: 'A' (elements/species/phases), 'C' (components), 'M' (models/constitution), 'P' (stable phases).
```

--------------------------------

### Example output for phase equilibrium data

Source: https://github.com/sundmanbo/opencalphad/blob/master/OCisoCbinding/pyOC/example.ipynb

Sample JSON-like output representing the structure of phase molar amounts, element compositions, site counts, and constituent compositions.

```json
(OpenCalphad being verbose): phases at equilibrium:
phase molar amounts:
{
    "FCC_A1#1": 0.01920542894617253,
    "M23C6": 0.02977621280681491,
    "M6C": 0.09441638360236765,
    "FCC_A1_AUTO#2": 0.856601974644645
}
phase element composition:
{
    "FCC_A1#1": {
        "C": 0.45665297099480046,
        "CR": 0.03426417107693683,
        "FE": 0.0020841630748334116,
        "MO": 0.1443298386826512,
        "SI": 6.681137603878831e-10,
        "V": 0.3626688555026644
    },
    "M23C6": {
        "C": 0.2068965517241379,
        "CR": 0.3414624222993837,
        "FE": 0.3838209757158874,
        "MO": 0.06769132200309422,
        "SI": 0.0,
        "V": 0.00012872825749663693
    },
    "M6C": {
        "C": 0.14285714285714285,
        "CR": 0.06508399462251023,
        "FE": 0.38133540345297173,
        "MO": 0.39191933121811307,
        "SI": 0.0,
        "V": 0.018804127849262088
    },
    "FCC_A1_AUTO#2": {
        "C": 0.013519853563065565,
        "CR": 0.050232768562391776,
        "FE": 0.9216963669684142,
        "MO": 0.009583081354863507,
        "SI": 0.003502209983129125,
        "V": 0.001465719568135902
    }
}
phase sites:
{
    "FCC_A1#1": [
        1.0,
        1.0
    ],
    "M23C6": [
        20.0,
        3.0,
        6.0
    ],
    "M6C": [
        2.0,
        2.0,
        2.0,
        1.0
    ],
    "FCC_A1_AUTO#2": [
        1.0,
        1.0
    ]
}
phase constituent composition:
{
    "FCC_A1#1": {
        "sublattice 0": {
            "CR": 0.06306130198166399,
            "FE": 0.0038357862720796564,
            "MO": 0.26563104420926176,
            "SI": 1.229626232816835e-09,
            "V": 0.6674718663073684
        },
        "sublattice 1": {
            "C": 0.8404444059091938,
            "VA": 0.15955559409080622
        }
    },
    "M23C6": {
        "sublattice 0": {
            "CR": 0.4730948138378144,
            "FE": 0.5268934005119624,
            "V": 1.1785650223144731e-05
        },
        "sublattice 1": {
            "CR": 0.14683798997528025,
            "FE": 0.19764676184049562,
            "MO": 0.654349446029911,
            "V": 0.0011658021543131923
        },
        "sublattice 2": {
            "C": 1.0
        }
    },
    "M6C": {
        "sublattice 0": {
            "FE": 1.0
        },
        "sublattice 1": {
            "MO": 1.0
        },
        "sublattice 2": {
            "CR": 0.2277939811787858,
            "FE": 0.33467391208540104,
            "MO": 0.37171765926339584,
            "V": 0.06581444747241731
        },
        "sublattice 3": {
            "C": 1.0
        }
    },
    "FCC_A1_AUTO#2": {
        "sublattice 0": {
            "CR": 0.050921215945224446,
            "FE": 0.9343283494325632,
            "MO": 0.00971441887551069,
            "SI": 0.0035502082791820494,
            "V": 0.0014858074675196773
        },
        "sublattice 1": {
            "C": 0.013705145118123152,
            "VA": 0.9862948548818768
        }
    }
}
```

--------------------------------

### Define Parameters for Carbon Phases

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

Example of defining Gibbs energy and LNTH parameters for carbon phases using multiple Einstein functions.

```OpenCalphad
PARAMETER G(GRAPHITE,C)    10 +GHSERCC; 6000 N 20HE !
PARAMETER LNTH(GRAPHITE,C) 10 LN(1953); 6000 N 20HE !
```

--------------------------------

### tqgetv - Get State Variable Values

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Retrieves equilibrium results including temperature, pressure, Gibbs energy, chemical potentials, phase amounts, and compositions.

```APIDOC
## tqgetv

### Description
Retrieves equilibrium results including temperature, pressure, Gibbs energy, chemical potentials, phase amounts, and compositions.

### Parameters
- **var** (character) - The state variable identifier (e.g., 'T', 'G', 'GM', 'MU', 'NP', 'X').
- **phtupx** (integer) - Phase tuple index; use -1 for all phases or 0 for global variables.
- **comp** (integer) - Component index; use -1 for all components.
- **n3** (integer) - Number of values to retrieve.
- **values** (double precision array) - Output array for retrieved values.
- **ceq** (type) - Equilibrium data pointer.
```

--------------------------------

### Print output for equilibrium calculations

Source: https://github.com/sundmanbo/opencalphad/blob/master/OCisoCbinding/pyOC/example.ipynb

Displays the results of the print statements from the equilibrium calculation example.

```text
n_C in FCC_A1#1 =  0.45665297099480046
a_i in FCC_A1#1 =  [1.0, 1.0]
y_V^0 in liquid =  0.6674718663073684
```

--------------------------------

### TPFUN Expression Example

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

An example of a TPFUN expression defining a thermodynamic parameter with temperature and pressure dependence, including a breakpoint and bibliographic reference. Ensure continuity at breakpoints.

```text
298.15 -8856.94+157.48*T-26.908*T*LN(T)+.00189435*T**2
        -1.47721E-06*T**3+139250*T**(-1); 2180 Y
        -34869.344+344.18*T-50*T*LN(T)-2.88526E+32*T**(-9); 6000 N 91Din
```

--------------------------------

### POST /calculate/no-global

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Calculates equilibrium without using the global grid minimizer for start constitutions.

```APIDOC
## POST /calculate/no-global

### Description
Calculates equilibrium using the current equilibrium as the start point, bypassing the global grid minimizer. Useful for small condition changes.

### Method
POST

### Endpoint
/calculate/no-global
```

--------------------------------

### GET /list/csv

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Exports STEP calculation results to a CSV file.

```APIDOC
## GET /list/csv

### Description
Lists the result from a STEP calculation in Comma Separated Value (CSV) format for external processing.

### Method
GET

### Endpoint
/list/csv

### Parameters
#### Query Parameters
- **independent_variable** (string) - Required - Single valued state variable (e.g., T).
- **dependent_variables** (string) - Required - Variables to list (e.g., NP(*), DGM(#)).
```

--------------------------------

### Example Macro for Site Fraction Condition

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

This macro, STEP8, shows how to set a condition on a constituent (site) fraction of a phase, specifically setting the constituent fraction of H2O in a gas phase. This is equivalent to setting its partial pressure in an ideal gas phase.

```text
STEP8
```

--------------------------------

### Get Phase Equilibrium Data with Python

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Retrieve and print phase amounts, compositions, sublattice sites, and constituent fractions from phase equilibrium data. Access constituent descriptions like mass and charge. This is useful for analyzing the results of equilibrium calculations.

```python
phasesAtEq = oc.getPhasesAtEquilibrium()
molarAmounts = phasesAtEq.getPhaseMolarAmounts()
print('Phase amounts:', molarAmounts)

compositions = phasesAtEq.getPhaseElementComposition()
for phase, comp in compositions.items():
    print(f'{phase}: {comp}')

sites = phasesAtEq.getPhaseSites()
constituentComp = phasesAtEq.getPhaseConstituentComposition()
print('Sublattice sites:', sites)
print('Constituent fractions:', constituentComp)

constituentsDesc = oc.getConstituentsDescription()
print('Vanadium mass:', constituentsDesc['V']['mass'])
print('Vanadium charge:', constituentsDesc['V']['charge'])
```

--------------------------------

### Example Macro for Gibbs Triangle

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

This macro demonstrates the use of the 'extra' subcommand for plot options, such as 'extra Gibbs-triangle y'. This syntax is new in OC version 5.048.

```text
extra Gibbs-triangle y
```

--------------------------------

### Example Macro for Constituent Fraction Condition

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

This macro, step9.OCM, demonstrates setting a condition on a constituent fraction, allowing for expressions necessary for calculating second-order transitions. It also tests a new expression for the SRO parameter.

```text
step9.OCM
```

--------------------------------

### Compute Transition Temperatures

Source: https://github.com/sundmanbo/opencalphad/blob/master/examples/TQ4lib/Cpp/Scheil/input.txt

Computes transition temperatures within specified parameters. Parameters include start temperature, end temperature, temperature step, and a value related to phase fraction or similar.

```OpenCalphad Computation
COMPUTE_TRANSITION_TEMPERATURES<1100.0/400.0/0.0010000/20 >
```

--------------------------------

### Configuration and Execution Commands

Source: https://github.com/sundmanbo/opencalphad/blob/master/examples/TQ4lib/Cpp/Scheil/input.txt

Endpoints for setting up the environment, defining thermodynamic systems, and running phase transition calculations.

```APIDOC
## Configuration Commands

### Description
Commands to define file paths, thermodynamic data, and system units.

### Parameters
- **DEFINE_OUTPUT_FILE_NAME** (string) - Name of the log file.
- **TDB_FILE_NAME** (string) - Name of the thermodynamic data file.
- **DEFINE_REF_ELEMENT** (string) - Reference element definition.
- **DEFINE_LIQUID_NAME** (string) - Name of the liquid phase.
- **DEFINE_SOLSOL_NAME** (string) - Name of the solid solution phase.
- **DEFINE_UNIT_COMPO_INPUT** (string) - Composition unit (e.g., W%).
- **DEFINE_UNIT_TEMP_INPUT** (string) - Temperature unit (C or K).
- **DEFINE_NCPU** (integer) - Number of CPUs to use.

## Calculation Commands

### Description
Commands to execute specific thermodynamic calculations.

### Parameters
- **DEFINE_COMPOSITION** (string) - Composition definition (e.g., MG=5/SI=1).
- **LIQUIDUS** (void) - Calculate liquidus temperature.
- **SOLIDUS** (void) - Calculate solidus temperature.
- **COMPUTE_TRANSITION_TEMPERATURES** (string) - Parameters: T_start/T_end/step/iterations.
- **COMPUTE_EQUILIBRIUM** (string) - Parameters: T/P.
- **SCHEIL_SOLIDIFICATION** (string) - Parameters: filename/fraction_solid/step/something.
```

--------------------------------

### GET /list/tpfun_symbols

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lists TPFUN expressions.

```APIDOC
## GET /list/tpfun_symbols

### Description
Lists all or specific TPFUN expressions. Use '*' for all or specific prefixes to filter.
```

--------------------------------

### Basic Equilibrium Calculation in C

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Demonstrates initializing OpenCalphad, reading a database, setting conditions (temperature, pressure, composition), performing an equilibrium calculation, and retrieving results like Gibbs energy, phase amounts, and chemical potentials. Ensure the 'crfe.TDB' database is accessible.

```c
#include "octqc.h"
#include <stdio.h>
#include <stdlib.h>

int main() {
    void *ceq;  // Equilibrium pointer
    int n, n1, n2, n3, cnum;
    double value, values[100];
    char phasename[25];

    // Initialize OpenCalphad
    c_tqini(0, &ceq);

    // Read database
    c_tqrfil("crfe.TDB", &ceq);

    // Check number of elements and phases
    printf("Elements: %d, Phases: %d\n", c_nel, c_ntup);

    // Set conditions
    c_tqsetc("T", 0, 0, 1000.0, &cnum, ceq);
    c_tqsetc("P", 0, 0, 1.0e5, &cnum, ceq);
    c_tqsetc("N", 0, 0, 1.0, &cnum, ceq);
    c_tqsetc("X", 1, 0, 0.3, &cnum, ceq);  // X(Cr)=0.3

    // Calculate equilibrium (n1>=0 uses grid minimizer)
    n1 = 0;
    c_tqce("", n1, 0, &value, &ceq);

    // Check for errors
    int err = c_errors_number();
    if (err != 0) {
        printf("Calculation failed with error: %d\n", err);
        c_reset_errors_number();
        return 1;
    }

    // Get Gibbs energy
    n3 = 1;
    c_tqgetv("G", 0, 0, &n3, values, &ceq);
    printf("Gibbs energy: %e J\n", values[0]);

    // Get phase amounts
    n3 = c_ntup;
    c_tqgetv("NP", -1, 0, &n3, values, &ceq);

    // List stable phases
    for (int i = 0; i < c_ntup; i++) {
        if (values[i] > 0.0) {
            c_tqgpn(i+1, phasename, &ceq);
            printf("Phase %s: %e mol\n", phasename, values[i]);
        }
    }

    // Get compositions
    n3 = c_nel;
    c_tqgetv("MU", -1, 0, &n3, values, &ceq);
    printf("Chemical potentials:\n");
    for (int i = 0; i < c_nel; i++) {
        printf("  %d: %e J/mol\n", i+1, values[i]);
    }

    // Clean up
    c_tqfree();

    return 0;
}

```

--------------------------------

### GET /list/symbols

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lists all state variable symbols and their expressions.

```APIDOC
## GET /list/symbols

### Description
Lists all state variable symbols and their associated expressions. Does not return calculated values.
```

--------------------------------

### Initialize pyOC Environment

Source: https://github.com/sundmanbo/opencalphad/blob/master/OCisoCbinding/pyOC/example.ipynb

Import necessary modules and set up the environment for OpenCalphad operations.

```python
import os
```

```python
import pyOC
from pyOC import opencalphad as oc
from pyOC import PhaseStatus as phStat
from pyOC import GridMinimizerStatus as gmStat
```

--------------------------------

### Manage Multiple Equilibria with tqcceq and tqselceq

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Demonstrates creating independent equilibrium records and switching between them for comparative calculations.

```fortran
program multiple_equilibria
  use liboctq
  implicit none
  type(gtp_equilibrium_data), pointer :: ceq, newceq
  integer :: n, n1, cnum
  double precision :: values(10)
  character(len=24) :: name

  call tqini(n, ceq)
  call tqrfil('crfe.TDB', ceq)

  ! Set up first equilibrium
  call tqsetc('T', 0, 0, 1000.0d0, cnum, ceq)
  call tqsetc('P', 0, 0, 1.0d5, cnum, ceq)
  call tqsetc('N', 0, 0, 1.0d0, cnum, ceq)
  call tqsetc('X', 1, 0, 0.3d0, cnum, ceq)
  call tqce(' ', 0, 0, values(1), ceq)

  ! Copy to new equilibrium record
  name = 'EQ2'
  call tqcceq(name, n1, newceq, ceq)
  write(*,*) 'Created equilibrium copy:', n1

  ! Modify conditions in the copy
  call tqsetc('T', 0, 0, 1200.0d0, cnum, newceq)
  call tqce(' ', 0, 0, values(1), newceq)

  ! Switch back to original equilibrium
  call tqselceq('DEFAULT', ceq)

  ! Compare results
  call tqgetv('G', 0, 0, n1, values, ceq)
  write(*,*) 'G at 1000K:', values(1)

  call tqselceq('EQ2', ceq)
  call tqgetv('G', 0, 0, n1, values, ceq)
  write(*,*) 'G at 1200K:', values(1)
end program multiple_equilibria
```

--------------------------------

### Open Online Help Browser

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

Use two question marks '??' to open the browser to the current menu in the online help facility. Ensure the OCHOME environment variable is set correctly.

```text
??
```

--------------------------------

### GET /list/state_variables

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lists the current values of individual state variables.

```APIDOC
## GET /list/state_variables

### Description
Lists values of individual state variables like G, HM, or X. Also supports listing calculated parameter identifiers like Curie temperatures or mobility logarithms.

### Method
GET

### Endpoint
/list/state_variables
```

--------------------------------

### Load Thermodynamic Database

Source: https://github.com/sundmanbo/opencalphad/blob/master/OCisoCbinding/pyOC/example.ipynb

Read a .tdb file from the environment path to initialize the thermodynamic system.

```python
tdbFile=os.environ.get('OCPUBLICDATA')+'/steel7.TDB'
oc.readtdb(tdbFile)
```

--------------------------------

### Comment in Macro File

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lines starting with '@$' are ignored by the OC software and can be used for comments.

```plaintext
@$ Ask user for the condition on the T
```

--------------------------------

### Enter Material Workflow

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Interactive session for defining a material and performing an equilibrium calculation.

```text
OC4:enter mat
Database:steel7
Elements: C , MO, V , CR, FE, SI,
Major element or material:fe
Input in mass percent? /Y/:
Input expected in mass percent

First alloying element:c
Mass percent: /1/:
Second alloying element:cr
Mass percent: /1/: 5
Third alloying element:mo
Mass percent: /1/: 8
Next alloying element:v
Mass percent: /1/:
Next alloying element:
 3E reading a TDB file
 3D em:  W%(C)=1  W%(CR)=5  W%(MO)=8  W%(V)=1   N=1
Temperature /1000/:
 3Y Constitution of metastable phases set
 3Y Composition set(s) created:           1
Gridmin:   18846 points   6.25E-02 s and       78 clockcycles, T= 1000.00
Phase change: its/add/remove:     5   0   21
Equilibrium calculation   19 its,   6.2500E-02 s and       94 clockcycles
```

--------------------------------

### Initialize OpenCalphad Workspace (Fortran)

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Initializes the OpenCalphad workspace and creates the default equilibrium record. This must be called before any other TQ routines. It returns an integer status and a pointer to the equilibrium data.

```fortran
program init_example
  use liboctq
  implicit none
  type(gtp_equilibrium_data), pointer :: ceq
  integer :: n

  ! Initialize workspace
  call tqini(n, ceq)
  if (gx%bmperr .ne. 0) then
    write(*,*) 'Initialization failed with error:', gx%bmperr
    stop
  endif

  write(*,*) 'OpenCalphad initialized successfully'
  write(*,*) 'Equilibrium name:', ceq%eqname
end program init_example
```

--------------------------------

### GET /list/results

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lists the results of an equilibrium calculation, including conditions, global data, component data, and stable phases.

```APIDOC
## GET /list/results

### Description
Lists the results of an equilibrium calculation. The output includes current conditions, global data, component specific data, and a list of stable phases with amounts, compositions, and constitutions.

### Method
GET

### Endpoint
/list/results

### Parameters
#### Query Parameters
- **option** (integer) - Required - Formatting option (1-9) defining output units (mole/mass fractions) and sorting order (value/alphabetical).
- **output** (string) - Optional - File path to write the output.
- **append** (string) - Optional - File path to append the output.
```

--------------------------------

### Set Initial Temperature and Pressure

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Local values of T (temperature) and P (pressure) can be set. These are not conditions but are used for commands like CALCULATE PHASE.

```text
--->OC5:set c t=1000 p=1e5
```

--------------------------------

### Set Scaled Coefficient

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Allows specifying a coefficient for optimization with a start value, scaling factor, and minimum/maximum values. Currently not implemented.

```APIDOC
## SET SCALED COEFFICIENT

### Description
Sets a coefficient for optimization, including a start value, scaling factor, and optional minimum and maximum values. The `SET VARIABLE` command sets the scaling factor equal to the start value and has no min or max values.

### Method
SET SCALED COEFFICIENT

### Endpoint
Not applicable (command-line interface)

### Parameters
None (Not implemented yet)

### Request Example
None (Not implemented yet)

### Response
None (Not implemented yet)
```

--------------------------------

### tqini - Initialize Workspace

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Initializes the OpenCalphad workspace and creates the default equilibrium record. This must be called before any other TQ routines.

```APIDOC
## tqini

### Description
Initializes the OpenCalphad workspace and creates the default equilibrium record.

### Parameters
- **n** (integer) - Output parameter for workspace index.
- **ceq** (gtp_equilibrium_data) - Pointer to the equilibrium data structure.
```

--------------------------------

### Stop in Macro File

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lines starting with '@&' create a stop point in the macro execution, allowing for inspection of output. The macro resumes after pressing ENTER/RETURN.

```plaintext
@&Input-new-temperature
```

--------------------------------

### Link OpenCalphad with Alternative Build Configurations

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

Use these specific make targets on Windows or UNIX to exclude popup windows or command-line editing features.

```text
linkmake-notinyfd
```

```text
linkpara-notinyfd
```

```text
Makefile-nogetkey
```

--------------------------------

### Show Commands

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Commands for displaying information.

```APIDOC
## Show Commands

### Description
Commands to display information about the system or its components.

### Endpoints
- `show property:`

### Parameters
- **property:** (string) - Displays specific properties.
```

--------------------------------

### Scheil Solidification Simulation in C++

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Implements a Scheil solidification calculator using a C++ class that wraps the OpenCalphad C API. It allows setting composition, calculating equilibrium at different temperatures, and retrieving the liquid fraction. Requires a database file like 'cost507r.TDB'.

```cpp
#include "octqc.h"
#include <iostream>
#include <vector>
#include <cmath>

class ScheilCalculator {
private:
    void* ceq;
    int nel, ntup;

public:
    ScheilCalculator(const char* database) {
        c_tqini(0, &ceq);
        c_tqrfil(database, &ceq);
        nel = c_nel;
        ntup = c_ntup;
    }

    void setComposition(double T, double P,
                       const std::vector<std::pair<int, double>>& composition) {
        int cnum;
        c_tqsetc("T", 0, 0, T, &cnum, ceq);
        c_tqsetc("P", 0, 0, P, &cnum, ceq);
        c_tqsetc("N", 0, 0, 1.0, &cnum, ceq);

        for (const auto& [compIdx, moleFrac] : composition) {
            c_tqsetc("X", compIdx, 0, moleFrac, &cnum, ceq);
        }
    }

    bool calculate() {
        double value;
        c_tqce("", 0, 0, &value, &ceq);
        return c_errors_number() == 0;
    }

    double getLiquidFraction() {
        int n3 = 1;
        double np;
        // Find liquid phase tuple index first
        for (int i = 1; i <= c_ntup; i++) {
            char pname[25];
            c_tqgpn(i, pname, &ceq);
            if (strncmp(pname, "LIQUID", 6) == 0) {
                c_tqgetv("NP", i, 0, &n3, &np, &ceq);
                return np;
            }
        }
        return 0.0;
    }

    void runScheil(double Tstart, double Tend, double dT) {
        std::cout << "T(K)\tLiquid_Fraction\n";

        double T = Tstart;
        while (T > Tend && getLiquidFraction() > 0.001) {
            int cnum;
            c_tqsetc("T", 0, 0, T, &cnum, ceq);

            if (calculate()) {
                double fliq = getLiquidFraction();
                std::cout << T << "\t" << fliq << "\n";
            }
            T -= dT;
        }
    }

    ~ScheilCalculator() {
        c_tqfree();
    }
};

int main() {
    ScheilCalculator calc("cost507r.TDB");

    // Al-Cu-Mg alloy
    std::vector<std::pair<int, double>> comp = {
        {1, 0.02},  // Cu
        {2, 0.03},  // Mg
    };

    calc.setComposition(1000.0, 1e5, comp);
    calc.calculate();
    calc.runScheil(900.0, 400.0, 5.0);

    return 0;
}

```

--------------------------------

### List Equilibrium Conditions

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Lists the current conditions for equilibrium calculation, including component amounts, temperature, and pressure. This command helps verify the input parameters before proceeding with calculations.

```text
--->OC5:l c
```

--------------------------------

### tqcceq / tqselceq - Copy and Select Equilibria

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Creates copies of equilibrium records and selects which one to use for calculations.

```APIDOC
## tqcceq / tqselceq

### Description
Creates copies of equilibrium records and selects which one to use for calculations.

### Methods
- **tqcceq(name, n1, newceq, ceq)**: Creates a copy of the current equilibrium record.
- **tqselceq(name, ceq)**: Switches the active equilibrium record.
```

--------------------------------

### User Input in Macro File

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Use '@?' followed by a prompt string to ask the user for input. The program waits for keyboard input, and the entered value is used for the subsequent command.

```plaintext
@?Input-new-temperature
```

--------------------------------

### List Ternary System Asymmetries (OC6)

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

Use this command to list the asymmetries of ternary systems. It helps in understanding the configuration of asymmetric cations within a ternary system.

```bash
--->OC6:l mq ms asym y                              
```

--------------------------------

### Calculate Phase Properties with tqcph1

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Computes Gibbs energy and its derivatives for a specific phase without performing a full equilibrium calculation. Requires initialization via tqini and database loading via tqrfil.

```fortran
program phase_properties
  use liboctq
  implicit none
  type(gtp_equilibrium_data), pointer :: ceq
  integer :: n, n1, n2, n3, cnum, nofc
  double precision :: gtp(6), dgdy(100), d2gdydt(100), d2gdydp(100), d2gdy2(5050)

  call tqini(n, ceq)
  call tqrfil('crfe.TDB', ceq)

  ! Set T and P conditions
  call tqsetc('T', 0, 0, 1000.0d0, cnum, ceq)
  call tqsetc('P', 0, 0, 1.0d5, cnum, ceq)

  ! Calculate phase properties
  ! n1 = phase tuple index
  ! n2 = calculation mode (0=G and T,P derivatives, 1=also composition derivatives, 2=also 2nd derivatives)
  n1 = 1
  n2 = 2
  call tqcph1(n1, n2, n3, gtp, dgdy, d2gdydt, d2gdydp, d2gdy2, ceq)

  write(*,*) 'Number of constituents:', n3
  write(*,*) 'G/RT:', gtp(1)
  write(*,*) 'dG/dT:', gtp(2)
  write(*,*) 'dG/dP:', gtp(3)
  write(*,*) 'd2G/dT2:', gtp(4)
  write(*,*) 'd2G/dTdP:', gtp(5)
  write(*,*) 'd2G/dP2:', gtp(6)

  ! First derivatives w.r.t. constituent fractions
  write(*,*) 'dG/dy:', (dgdy(n), n=1,n3)
end program phase_properties
```

--------------------------------

### POST /calculate/all-equilibria

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Calculates all equilibria with non-zero weight as defined by the current range settings.

```APIDOC
## POST /calculate/all-equilibria

### Description
Calculates all equilibria with non-zero weight. Intended for assessment procedures and testing parallelization.

### Method
POST

### Endpoint
/calculate/all-equilibria
```

--------------------------------

### tqce - Calculate Equilibrium

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Calculates thermodynamic equilibrium using the set conditions. Uses grid minimization by default to find the global minimum.

```APIDOC
## tqce

### Description
Performs the equilibrium calculation based on previously defined conditions.

### Parameters
- **target** (character) - Target string for calculation.
- **n1** (integer) - Minimizer control (0 for grid minimizer, -1 to skip).
- **n2** (integer) - Secondary control parameter.
- **value** (double precision) - Resulting value.
- **ceq** (gtp_equilibrium_data) - Pointer to the equilibrium data structure.
```

--------------------------------

### Set Commands

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Commands for setting various parameters and configurations.

```APIDOC
## Set Commands

### Description
Commands to set various parameters, options, and configurations within the system.

### Endpoints
- `set Advanced`
- `set As start equilibrium`
- `set Axis`
- `set Bit`
- `set Condition`
- `set Echo`
- `set Fixed coefficient`
- `set initial_T_and_P`
- `set Input-Amounts`
- `set Interactive`
- `set Log-File`
- `set Numeric-Options`
- `set Optimizing conditions`
- `set system variable`
- `set Phase "phase-name"`
- `set Quit`
- `set Range of experimental equilibria`
- `set Reference-State`
- `set Scaled coefficient`
- `set Status`
- `set Units`
- `set Variable coefficient`
- `set Verbose`
- `set Weight`

### Sub-Commands for `set Advanced`:
- `set advanced EEC-method`
- `set advanced equilibrium transfer`
- `set advanced global-min-onoff`
- `set advanced grid_density`
- `set advanced help-popup-off`
- `set advanced level`
- `set advanced map-special`
- `set advanced no-macro-stop`
- `set advanced open-popup-off`
- `set advanced quit`
- `set advanced symbol`
- `set advanced working-directory`

### Sub-Commands for `set Phase "phase-name"`:
- `set phase ... Amount`
- `set phase ... Bits`
- `set phase ... Constitution`
- `set phase ... Default-constitution`
- `set phase ... Quit`
- `set phase ... Status`

### Sub-Commands for `set Status`:
- `set status Constituent`
- `set status Element`
- `set status Phases`
- `set status Species`

### Parameters
- **Advanced** (string) - Accesses advanced settings.
- **As start equilibrium** (string) - Sets as starting equilibrium.
- **Axis** (string) - Sets axis properties.
- **Bit** (string) - Sets bit options.
- **Condition** (string) - Sets conditions.
- **Echo** (string) - Sets echo behavior.
- **Fixed coefficient** (string) - Sets fixed coefficients.
- **initial_T_and_P** (string) - Sets initial Temperature and Pressure.
- **Input-Amounts** (string) - Sets input amounts.
- **Interactive** (string) - Sets interactive mode.
- **Log-File** (string) - Sets the log file.
- **Numeric-Options** (string) - Sets numeric options.
- **Optimizing conditions** (string) - Sets optimizing conditions.
- **system variable** (string) - Sets system variables.
- **Phase "phase-name"** (string) - Sets properties for a specific phase.
- **Quit** (boolean) - Quits the set operation.
- **Range of experimental equilibria** (string) - Sets the range for experimental equilibria.
- **Reference-State** (string) - Sets the reference state.
- **Scaled coefficient** (string) - Sets scaled coefficients.
- **Status** (string) - Sets status information.
- **Units** (string) - Sets the units.
- **Variable coefficient** (string) - Sets variable coefficients.
- **Verbose** (string) - Sets verbose output.
- **Weight** (string) - Sets weight.
```

--------------------------------

### Retrieve Equilibrium State Variables with tqgetv

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Retrieves thermodynamic properties like temperature, Gibbs energy, chemical potentials, and phase compositions after equilibrium calculation.

```fortran
program get_results
  use liboctq
  implicit none
  type(gtp_equilibrium_data), pointer :: ceq
  integer :: n, n1, n2, n3, cnum, i
  double precision :: values(100), temp, gibbs
  character(len=24) :: statevar, phasename

  call tqini(n, ceq)
  call tqrfil('crfe.TDB', ceq)

  ! Set conditions and calculate
  call tqsetc('T', 0, 0, 1000.0d0, cnum, ceq)
  call tqsetc('P', 0, 0, 1.0d5, cnum, ceq)
  call tqsetc('N', 0, 0, 1.0d0, cnum, ceq)
  call tqsetc('X', 1, 0, 0.3d0, cnum, ceq)
  call tqce(' ', 0, 0, temp, ceq)

  ! Get temperature
  call tqgetv('T', 0, 0, n3, values, ceq)
  write(*,*) 'Temperature:', values(1), 'K'

  ! Get total Gibbs energy
  call tqgetv('G', 0, 0, n3, values, ceq)
  write(*,*) 'Gibbs energy:', values(1), 'J'

  ! Get Gibbs energy per mole
  call tqgetv('GM', 0, 0, n3, values, ceq)
  write(*,*) 'Gibbs energy/mol:', values(1), 'J/mol'

  ! Get chemical potentials of all components
  n3 = nel
  call tqgetv('MU', -1, 0, n3, values, ceq)
  write(*,*) 'Chemical potentials:'
  do i = 1, n3
    write(*,*) '  ', cnam(i), ':', values(i)
  enddo

  ! Get phase amounts for all phases
  n3 = ntup
  call tqgetv('NP', -1, 0, n3, values, ceq)
  write(*,*) 'Phase amounts:'
  do i = 1, n3
    if (values(i) .gt. 0.0d0) then
      call tqgpn(i, phasename, ceq)
      write(*,*) '  ', trim(phasename), ':', values(i)
    endif
  enddo

  ! Get composition of specific phase (phase tuple index 1)
  n3 = nel
  call tqgetv('X', 1, -1, n3, values, ceq)
  write(*,*) 'Phase 1 composition:', (values(i), i=1,n3)
end program get_results
```

--------------------------------

### Set Thermodynamic Conditions

Source: https://github.com/sundmanbo/opencalphad/blob/master/OCisoCbinding/pyOC/example.ipynb

Define the pressure and temperature for the system state.

```python
oc.setPressure(1E5)
oc.setTemperature(1173)
```

--------------------------------

### Show Property Values in OpenCalphad

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Use the 'show' command to display the values of state variables, user-defined symbols, or model parameters. Properties are separated by spaces. This is similar to the LIST state-variables command.

```text
OC5:show t g tc(bcc) x(bcc,cr) mu(cr) cp
T=  1.2000000E+03
G= -5.9565761E+04
TC(BCC_A2)=  1.0272646E+03
X(BCC_A2,CR)=  3.100000E-2
MU(CR)= -7.2489667E+04
CP=     4.08487869E+01
```

--------------------------------

### Selection Commands

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

Commands for selecting various system components or settings.

```APIDOC
## Select Commands

### Description
Commands to select specific options or components within the system.

### Endpoints
- `select Equilibrium`
- `select Graphics`
- `select Language`
- `select Minimizer`
- `select Optimizer`

### Parameters
- **Equilibrium** (string) - Selects equilibrium settings.
- **Graphics** (string) - Selects graphics options.
- **Language** (string) - Selects the language.
- **Minimizer** (string) - Selects the minimizer.
- **Optimizer** (string) - Selects the optimizer.
```

--------------------------------

### Manipulate Equilibrium Records and Calculate Gibbs Energy with Python

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Change the active equilibrium record, set temperature, calculate equilibrium, and retrieve Gibbs energy. This allows for comparing thermodynamic properties at different conditions or equilibrium states.

```python
oc.changeEquilibriumRecord('eq2', copiedEqName='default equilibrium')
oc.setTemperature(1273)
oc.calculateEquilibrium()
G2 = oc.getGibbsEnergy()

oc.changeEquilibriumRecord()
G1 = oc.getGibbsEnergy()
print(f'G at 1173K: {G1:.2e}, G at 1273K: {G2:.2e}')
```

--------------------------------

### List Ternary System Asymmetries (Post-Amend)

Source: https://github.com/sundmanbo/opencalphad/blob/master/changes.txt

Lists the asymmetries of ternary systems after an amendment, showing the updated configuration. This command is used to verify changes made to the system.

```bash
--->OC6:l mq ms asym                     
```

--------------------------------

### Calculate Equilibrium (Fortran)

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Calculates thermodynamic equilibrium using the set conditions. Uses grid minimization by default to find the global minimum. Set the `n1` parameter to 0 or a positive value for grid minimization, or -1 to disable it.

```fortran
program calculate_equilibrium
  use liboctq
  implicit none
  type(gtp_equilibrium_data), pointer :: ceq
  integer :: n, n1, n2, cnum
  double precision :: value
  character(len=60) :: target

  call tqini(n, ceq)
  call tqrfil('crfe.TDB', ceq)

  ! Set conditions
  call tqsetc('T', 0, 0, 1000.0d0, cnum, ceq)
  call tqsetc('P', 0, 0, 1.0d5, cnum, ceq)
  call tqsetc('N', 0, 0, 1.0d0, cnum, ceq)
  call tqsetc('X', 1, 0, 0.3d0, cnum, ceq)

  ! Calculate equilibrium with grid minimizer (n1=0 or positive)
  target = ' '
  n1 = 0  ! Use grid minimizer
  n2 = 0
  call tqce(target, n1, n2, value, ceq)

  if (gx%bmperr .ne. 0) then
    write(*,*) 'Calculation failed:', gx%bmperr
  else
    write(*,*) 'Equilibrium calculated successfully'
  endif

  ! To calculate without grid minimizer, set n1 = -1
  ! call tqce(target, -1, n2, value, ceq)
end program calculate_equilibrium
```

--------------------------------

### SHOW Command

Source: https://github.com/sundmanbo/opencalphad/blob/master/doc/manual/ochelp.html

The SHOW command displays the current value of state variables, user-defined symbols, or model parameters.

```APIDOC
## SHOW

### Description
Displays the value of a property, state variable (e.g., T, G), or model parameter. Multiple properties can be specified on the same line separated by spaces.

### Parameters
#### Query Parameters
- **properties** (string) - Required - A space-separated list of properties or symbols to display (e.g., 't g tc(bcc)').
```

--------------------------------

### Compile and Link C++ TQ Interface

Source: https://github.com/sundmanbo/opencalphad/blob/master/examples/TQ4lib/Cpp/Matthias/readme.txt

Command to compile and link the main C++ program with the required Fortran TQ libraries and standard system libraries.

```bash
g++ -o tqintf -lstdc++ tqintf.cpp liboctqiso.o liboctq.o liboceq.a -lgfortran -lm
```

--------------------------------

### Read TDB Database File (Fortran)

Source: https://context7.com/sundmanbo/opencalphad/llms.txt

Reads a thermodynamic database file in TDB format. Use `tqrfil` to read all elements or `tqrpfil` to read only selected elements. Ensure the database file exists and is accessible.

```fortran
program read_database
  use liboctq
  implicit none
  type(gtp_equilibrium_data), pointer :: ceq
  character(len=60) :: filename
  character(len=2) :: selel(3)
  integer :: n, nsel

  call tqini(n, ceq)

  ! Read all elements from database
  filename = 'steel7.TDB'
  call tqrfil(filename, ceq)
  if (gx%bmperr .ne. 0) goto 1000

  write(*,*) 'Number of elements:', nel
  write(*,*) 'Number of phase tuples:', ntup

  ! Alternatively, read only selected elements
  ! selel = (/'FE', 'CR', 'NI' /)
  ! nsel = 3
  ! call tqrpfil(filename, nsel, selel, ceq)

1000 continue
end program read_database
```

--------------------------------

### Compute Equilibrium

Source: https://github.com/sundmanbo/opencalphad/blob/master/examples/TQ4lib/Cpp/Scheil/input.txt

Computes the equilibrium state at a given temperature and pressure.

```OpenCalphad Computation
COMPUTE_EQUILIBRIUM<500/3>
```
Tokens:
Raw