> For the complete documentation index, see [llms.txt](https://devdocs.olisystems.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://devdocs.olisystems.com/chemistry-model-files/chembuilder-api/getting-started-with-chembuilder/choose-solids.md).

# Choose Solids

You can include or exclude solid phases in your calculation. Here's an example demonstrating how to include or exclude a particular solid phase of a species.<br>

The example below illustrates how to include specific solid phases in the system.

```json
{
  "params": {
    "thermodynamicFramework": "MSE (H3O+ ion)",
    "privateDatabanks": [
    ],
    "modelName": "testModel",
    "phases": [
      "liquid1",
      "vapor",
      "solid",
      "liquid2"
    ],
    "inflows": [
      {
        "name": "H2O"
      },
      {
        "name": "NACL"
      },
      {
        "name": "UREA"
      },
      {
        "name": "NH3"
      },
      {
        "name": "CO2"
      },
      {
        "name": "CACO3"
      },
      {
        "name": "Benzene"
      },
      {
        "name": "Ethanol"
      }
    ],
    "includedSolids": {
      "enabled": true,
      "solids": [
        "NACLPPT",
        "NAOHPPT",
        "CACO3PPT",
        "UREAPPT"
      ]
    }
  }
}

```

{% hint style="info" %}
The "`includedSolids`" and "`excludedSolids`" parameters are optional in the input file for generating a .dbs file. Note that you cannot use "`includedSolids`" and "`excludedSolids`" simultaneously.
{% endhint %}

{% hint style="warning" %}
"includedSolids" will only include the solid phases of species explicitly specified by the user. An unspecified solid phase of species will be excluded by default.
{% endhint %}

The example below illustrates how to exclude certain solid phases in the system.

```json
{
  "params": {
    "thermodynamicFramework": "MSE (H3O+ ion)",
    "privateDatabanks": [
      "URE"
    ],
    "modelName": "testModel",
    "phases": [
      "liquid1",
      "vapor",
      "solid",
      "liquid2"
    ],
    "inflows": [
      {
        "name": "H2O"
      },
      {
        "name": "NACL"
      },
      {
        "name": "UREA"
      },
      {
        "name": "NH3"
      },
      {
        "name": "CO2"
      },
      {
        "name": "CACO3"
      },
      {
        "name": "Benzene"
      },
      {
        "name": "Ethanol"
      }
    ],
    "excludedSolids": {
      "enabled": true,
      "solids": [
        "CACL2.6H2O",
        "UREA"
      ]
    }
  }
}
```

{% hint style="warning" %}
"excludedSolids" will only exclude the solid phases of species explicitly specified by the user. An unspecified solid phase of species will be included by default.
{% endhint %}