Suggestion for read and transform trajectory

[JianxingHuang]

It takes quite a long time to read and transfrom the 'trajectory.xyz' file. I would suggest to use the method provided by pymatgen/ase, which is faster. The code example is shown below:

from ase.io import read, write  
import numpy as np
from pymatgen.io.ase import AseAtomsAdaptor
from ase import Atoms
from pymatgen.io.lammps.outputs import parse_lammps_dumps
confs = parse_lammps_dumps('trajectory.xyz') # this is a generator
symbols = ['La'] *24 +['Zr'] * 16 + ['O'] *96 + ['Li']*56
ats = [Atoms(symbols=symbols, positions=conf.data.values[:, :3],
             cell=conf.box.to_lattice().matrix, pbc=True) for conf in confs]
write('LLZO.xyz', ats)
ats = read('LLZO.xyz', ':100')

Besides, I suggest to rename the 'trajectory.xyz' as 'dump.trajectory'. For it is more like a lammps-dump output rather than '.xyz' type file. Because '.xyz' hints the user to use ase.io.read to load the data.