def METHOD_NAME(self) -> str:
    """Generate the XYZ representation of the logfile data."""
    # Options for output (to a single file):
    # 1. Write all geometries from an optimization, which programs like VMD
    #   can read in like a trajectory.
    # 2. Write the final converged geometry, which for any job other than
    #   a geometry optimization would be the single/only geometry.
    # 3. Write the very first geometry, which for any job other than a
    #   geometry optimization would be the single/only geometry.
    # 4. Write the first and last geometries from a geometry optimization.
    # 5. Write arbitrary structures via zero-based indexing.
    # TODO: Options for output (to multiple files)
    xyzblock = []
    lencoords = len(self.ccdata.atomcoords)
    # Collect the indices.
    if lencoords == 1 or self.do_firstgeom:
        self.indices.add(0)
    if self.do_lastgeom:
        self.indices.add(lencoords - 1)
    if self.do_allgeom:
        for i in range(lencoords):
            self.indices.add(i)
    # Generate the XYZ string for each index.
    indices = sorted(self.indices)
    if not indices:
        indices = [-1]
    for i in indices:
        xyzblock.append(self._xyz_from_ccdata(i))
    # Ensure an extra newline at the very end.
    xyzblock.append('')
    return '\n'.join(xyzblock)