Confusion with As2Se3 data

#1

Hello

I’m working with As2Se3 and I was confused by the data available at https://materialsproject.org/materials/mp-909/#.

The material has a monoclinic crystal structure, and on the home page the beta angle appears to be 90.399 °. However, by downloading .CIF or VASP inputs, the beta appears to be 110.15º.

Is there any error in the data or is there something I’m not understanding? Thank you very much.

1 Like
#2

Hi Murilo,

The two cells are equivalent – it’s a setting issue. The different beta angle accompanies a different c length. You can see below that the two cells have identical volume and space group.

We normally show cell coordinates as computed on the upper right of a material’s detail page, whereas we show the output of pymatgen transformations (such as get_conventional_standard_structure) in the structure viewer to aid in visualization.

Best,
Donny
MP team

from pymatgen import MPRester
from pymatgen.symmetry.analyzer import SpacegroupAnalyzer

mpr = MPRester()
structure = mpr.get_structure_by_material_id("mp-909")
sga = SpacegroupAnalyzer(structure)
print(repr(structure.lattice))
conv_std_structure = sga.get_conventional_standard_structure()
print(repr(conv_std_structure.lattice))
Lattice
    abc : 4.5049584136820995 10.96764885 12.135673622199805
 angles : 90.0 90.39908626304369 90.0
 volume : 599.5945493432381
      A : 4.50483347 0.0 -0.0335517
      B : 0.0 10.96764885 0.0
      C : 0.00585457 0.0 12.13567221
Lattice
    abc : 4.5049584136820995 10.96764885 12.915402720502435
 angles : 90.0 110.01464391353814 90.0
 volume : 599.5945493432381
      A : 0.0 4.5049584136820995 0.0
      B : 10.96764885 0.0 0.0
      C : 0.0 -4.42042964883418 -12.135379233978204
structure.get_space_group_info() == conv_std_structure.get_space_group_info()
True
1 Like
#3

The atomic positions in fractional coordinates are they the same in both cells?