QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: atk_user on November 14, 2014, 12:48

Title: Band structure (route) setup
Post by: atk_user on November 14, 2014, 12:48

Dear, all

I try to calculate the band structure from the optimized structures. (orthorhombic structure). However, there is no guide line to setup the k-path (e.g., G, X, Z, ...). From the wikipedia, the high symmetry points for simple orthorhombic system is represented by (G -> X -> U -> Z ->G ) http://en.wikipedia.org/wiki/Brillouin_zone#mediaviewer/File:Simple_Orthorhombic_Lattice_(Brillouin_zone).png (http://en.wikipedia.org/wiki/Brillouin_zone#mediaviewer/File:Simple_Orthorhombic_Lattice_(Brillouin_zone).png)
Is it right? How can I check the path is right?


Actually, I wanted to calculate the band along the k-path [0,0,0] -> [0,0.5,0] -> [0,0,0.5] -> [0,0,0].
However, I got the error message using below input file.

The error is about the using of "points_per_segment=20,"

Why it cannot use "points_per_segment=20," with kpoints option?


configuration = nlread('../analysis.nc', object_id='gID001')[0]

# -------------------------------------------------------------
# Bandstructure
# -------------------------------------------------------------
bandstructure = Bandstructure(
    configuration=configuration,
    kpoints=[[0.0,0.0,0.0],[0.0,0.5,0.0],[0.0,0.5,0.5],[0.0,0.0,0.5],[0.0,0.0,0.0]],
    points_per_segment=20,
    bands_above_fermi_level=All,
    projection_list=ProjectionList(elements=[Lanthanum,Manganese,Strontium,Oxygen]),
    )
nlsave('0Vo_Band_LSMO_part.nc', bandstructure)

Title: Re: Band structure (route) setup
Post by: Anders Blom on November 14, 2014, 13:53

Currently, the route settings is a bit limited in ATK. You can only either do route+points_per_segment, or k_points.

For your purpose, I would stick to the route+points though. If you want GXUZG route, just use

Code: python

bandstructure = Bandstructure(
    configuration=configuration,
    route=['G','X','U','Z','G'],
    points_per_segment=20,
    bands_above_fermi_level=All,
    projection_list=ProjectionList(elements=[Lanthanum,Manganese,Strontium,Oxygen]),
    )

If you want the route you indicated, just use
    route=['G','Y','Z','G']
because that's what these k-points are called.

Title: Re: Band structure (route) setup
Post by: atk_user on November 14, 2014, 14:01

Then.....

How can I call the same points in hexagonal symmetry?


[0,0,0] -> [0,0.5,0] -> [0,0,0.5] -> [0,0,0]. in hexagonal?

Title: Re: Band structure (route) setup
Post by: Anders Blom on November 14, 2014, 14:24

G-M-A-G

Title: Re: Band structure (route) setup
Post by: atk_user on November 14, 2014, 14:28

I missing a point (0, 0.5, 0.5)

How can I call that point in orthorhombic and hexagonal symmetry.

Is there any guide line or manual to assign that points?

Title: Re: Band structure (route) setup
Post by: atk_user on November 14, 2014, 14:37

That's the T and L point I think.

Title: Re: Band structure (route) setup
Post by: Anders Blom on November 14, 2014, 14:37

T and L

http://www.cryst.ehu.es/cryst/get_kvec.html

Or attached doc

Title: Re: Band structure (route) setup
Post by: atk_user on November 14, 2014, 14:38

I see  :) how can I assign the name of points.

Thank you very much for your time.

Title: Re: Band structure (route) setup
Post by: Anders Blom on November 14, 2014, 14:40

That's the point - you don't have to do that, they are already defined in ATK. So you just do

route=['G','L','T',...]

(not in the same one though, L and T are for different systems, but just as a concept).

Title: Re: Band structure (route) setup
Post by: atk_user on November 14, 2014, 14:49

I got the error messages for the route setup.

bandstructure = Bandstructure(
    configuration=configuration,
    route=['G', 'X', 'S', 'Y', 'G'],
    points_per_segment=20,
    bands_above_fermi_level=4,
    )
nlsave('Band_GXSYG.nc', bandstructure)



Traceback (most recent call last):
  File "input.py", line 12, in <module>
    projection_list=ProjectionList(elements=[Lanthanum,Manganese,Strontium,Oxygen]),
  File "./zipdir/NL/Analysis/Bandstructure.py", line 67, in __init__
  File "./zipdir/NL/Analysis/BaseBandstructure.py", line 71, in __init__
  File "./zipdir/NL/Analysis/BaseBandstructure.py", line 495, in setupPathMethod
  File "./zipdir/NL/Analysis/BaseBandstructure.py", line 429, in determinePath
KeyError: 'S'

Title: Re: Band structure (route) setup
Post by: Anders Blom on November 14, 2014, 15:51

Is your bulk configuration a SimpleOrthorhombic class? Else it will not work.

Title: Re: Band structure (route) setup
Post by: atk_user on November 14, 2014, 16:04

Actually, my system is slightly distorted,

alpha, beta, gamma is 89.95, 90.05, 89.92 and a, b, and c are 8.04, 8.04, and 23.29 ..

The route G Z T, Y G is calculated.

Title: Re: Band structure (route) setup
Post by: Anders Blom on November 16, 2014, 23:40

Are your angles distorted on purpose or by accident?