Get the indices of all points in a fractional coord list that are
    equal to a fractional coord (with a tolerance), taking into account
    periodic boundary conditions.

    Args:
        fcoord_list: List of fractional coords
        fcoord: A specific fractional coord to test.
        atol: Absolute tolerance. Defaults to 1e-8.

    Returns:
        Indices of matches, e.g., [0, 1, 2, 3]. Empty list if not found.

def find_in_coord_list_pbc(fcoord_list, fcoord, atol=1e-8):
    """
    Get the indices of all points in a fractional coord list that are
    equal to a fractional coord (with a tolerance), taking into account
    periodic boundary conditions.

    Args:
        fcoord_list: List of fractional coords
        fcoord: A specific fractional coord to test.
        atol: Absolute tolerance. Defaults to 1e-8.

    Returns:
        Indices of matches, e.g., [0, 1, 2, 3]. Empty list if not found.
    """
    if len(fcoord_list) == 0:
        return []
    fcoords = np.tile(fcoord, (len(fcoord_list), 1))
    fdist = fcoord_list - fcoords
    fdist -= np.round(fdist)
    return np.where(np.all(np.abs(fdist) < atol, axis=1))[0]