# k-points (`kpoints.in`

)¶

This file is used to specify the k points needed for phonon calculations.

## File format¶

The format of this file must be as follows:

```
N_kpoints
kx(0) ky(0) kz(0)
kx(1) ky(1) kz(1)
...
kx(N_kpoints-1) ky(N_kpoints-1) kz(N_kpoints-1)
```

Here,
* `N_kpoints`

is the number of k points you want to consider.
* The remaining lines give the k vectors (in units of 1/Å) you want to consider.
* The user has to make sure that the k vectors are defined in the reciprocal space with respect to the unit cell chosen.