## Interstitial get started and input examples

`Interstitial` calculates the energy difference when adding an atom into the crystal structure. We need to give the information of `supercell` (default value is [1, 1, 1]) and `insert_ele` list for the element types of the atoms added in.

#### An example of the input file for Interstitial by deepmd:

```json
{
  "structures": "confs/mp-*",
  "interaction": {
    "type": "deepmd",
    "model": "frozen_model.pb",
    "type_map": {
      "Al": 0,
      "Mg": 1
    }
  },
  "properties": [
    {
      "type": "interstitial",
      "supercell": [
        3,
        3,
        3
      ],
      "insert_ele": [
        "Al"
      ],
      "conf_filters": {
        "min_dist": 1.5
      },
      "cal_setting": {
        "input_prop": "lammps_input/lammps_high"
      }
    }
  ]
}
```

We add a `conf_filters` parameter in `properties` part and this parameter can help to eliminate undesirable structure which can render rather difficult convergence in calculations. In the example above, **"min_dist": 1.5** means if the smallest atomic distance in the structure is less than 1.5 angstrom, the configuration would be eliminated and not used in calculations.