def create_model(translation_vectors, comment, lattice_parameter, units=1, atom_type='Si', filename=None):
a = lattice_parameter
eps = 1e-6
points = []
for x in range(units+1):
for y in range(units+1):
for z in range(units+1):
for tv in translation_vectors:
point = ( (tv[0]+x)*a, (tv[1]+y)*a, (tv[2]+z)*a )
if point[0] <= units*a+eps and point[1] <= units*a+eps and point[2] <= units*a+eps:
points.append(point)
atoms = [Atom(i, atom_type, x,y,z) for i,(x,y,z) in enumerate(points)]
m = Model(comment=comment, xsize=units*a, ysize=units*a, zsize=units*a, atoms=atoms)
m.recenter()
return m
