# Program Input¶

## List of possible input flags¶

The UNIFAC program accepts a few additional flags to specify system conditions, choose a template for the calculation, or set the number of points taken over a provided range (e.g., a temperature range). A summary of these input options is provided below. In the following section, examples are given for each flag.

Flag |
Meaning |
---|---|

-t |
One of a number of template strings to indicate the problem type |

-temperature |
One/two values (K) to specify the system temperature/temperature range |

-steps |
the number of steps taken if a range is specified or for a BINMIXCOEF or TERNARYMIX calculation |

-preset |
an integer to indicate which solvent system is chosen for logP calculations |

## Examples of general program flags¶

In this section, we provide a brief example of each of the above flags.

### -t¶

The -t flag has been shown in previous examples and will be described in more detail in the following section. The -t flag must be followed by one of the following template names:

```
LOGP
ACTIVITYCOEF
PURESOLUBILITY
SOLUBILITY
VAPORPRESSURE
PUREVAPORPRESSURE
BINMIXCOEF
TERNARYMIX
```

A brief example of this for the ACTIVITYCOEF template is given below:

```
$AMSBIN/unifac -smiles "CCCCO" "CCCOCCC" -frac 0.5 0.5 -t SOLUBILITY
```

### -temperature¶

In this example, we take the previous DDT solubility calculation and perform the calculation at a temperature of 310 K. This is shown below:

```
$AMSBIN/unifac -smiles \
"C1=CC(=CC=C1C(C2=CC=C(C=C2)Cl)C(Cl)(Cl)Cl)Cl" -hfusion 26.28 -meltingpoint 383 \
"CCO" -frac 0.0 1.0 -temperature 310 -t SOLUBILITY
```

If we want to calculate the solubility over a temperature range (say, 310-350 K), we need to specify the temperature flag twice and also include a number of steps to take between the two temperatures with the -steps flag. This looks like the following:

```
$AMSBIN/unifac -smiles \
"C1=CC(=CC=C1C(C2=CC=C(C=C2)Cl)C(Cl)(Cl)Cl)Cl" -hfusion 26.28 -meltingpoint 383 \
"CCO" -frac 0.0 1.0 -temperature 310 -temperature 350 -steps 10 -t SOLUBILITY
```

### -steps¶

The -steps flag specifies a number of steps to take between a temperature range or the number of steps to take along each mole fraction axis for a BINMIXCOEF or a TERNARYMIX calculation. For an input value of N for the -steps flag, the BINMIXCOEF and TERNARYMIX templates consider the following number of distinct mole fraction combinations:

Template |
Number of distinct systems considered |
---|---|

BINMIXCOEF |
N+5 |

TERNARYMIX |
(N+1)(N+2)/2 |

If we wanted to calculate the thermodynamic properties of a binary mixture with a very small step size, we could input a N value of 1000 to take 1005 samples of the mole fraction space:

```
$AMSBIN/unifac -smiles \
"CCCCOCC" -antoine 5 1500 30 \
"CCCCCC" -antoine 6 1234 10 \
-t BINMIXCOEF -steps 1000
```

### -preset¶

The preset flag is used for a logP calculation. A preset of 2 (default) indicates that that we do a logP calculation on the traditional Octanol/Water system. This looks like the following:

```
$AMSBIN/unifac -smiles "CCCCOCC" -t LOGP -preset 2
```

More information on the preset flag options for the LOGP template will be given in the templates section.