QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: jerry on September 16, 2012, 13:50

Title: K point setting in band structure calculation
Post by: jerry on September 16, 2012, 13:50

Dear,

 I want to know how to set the Brillouin zone route in calculating the band structure of graphene.

Thanks

Title: Re: K point setting in band structure calculation
Post by: Nordland on September 16, 2012, 20:48

Have you tried using VNL in the scripter?

Title: Re: K point setting in band structure calculation
Post by: ams_nanolab on September 18, 2012, 15:20

Usually symmetry point routes can be found built in in the BandStructure Analysis tool depending on the material of choice (lattice type) just have to input the points e.g. G, M, K, G in the box "brillouin zone route" to get the desired symmetry points path in the E-k relation.

see

http://www.quantumwise.com/publications/tutorials/mini-tutorials/167-transmission-spectrum-of-perfect-sheets-of-graphene-and-mos2

for help

 :)

Title: Re: K point setting in band structure calculation
Post by: jerry on September 26, 2012, 12:38

Thank you very much for your help. I want to calculate the bloch state for the BN sheet, which is built through substituting the two carbon atoms of graphene sheet from the database and then optimizing the geometry. I have calculated the band structure with the route (G, K, M, G). Now i want to calculate the bloch state at the K point and M point with certain quantum numbers. How i can choose the K point and the M point using the blochstate calculator within VNL?

Thank you very much

Title: Re: K point setting in band structure calculation
Post by: Anders Blom on September 26, 2012, 13:30

K = (0.333333, 0.333333, 0)
M = (0, 0.5, 0)

Enter this for kA, kB, kC in the Bloch State dialog, then your quantum number = band index

Title: Re: K point setting in band structure calculation
Post by: jerry on September 27, 2012, 02:12

Thank you very much! What if i repeat this model along the A and B axes for 2 or three time? Then How should i set the band structure route? 

Title: Re: K point setting in band structure calculation
Post by: zh on September 27, 2012, 07:42

You can choose the k-points and route same to those used for the band structure structure of a primitive cell, if the coordinates of  k points are given with respect to the reciprocal lattice vectors, i.e., the fractional coordinates.

Title: Re: K point setting in band structure calculation
Post by: Anders Blom on September 27, 2012, 10:01

For the band structure (as opposed to the Bloch state) you cannot enter k-points directly, only symmetry points. If you repeat the lattice, the crystal class changes to UnitCell, which has no real predefined symmetry points. You can however easily work around this by switching the crystal class in Bulk Tools>Lattice Parameters in the Builder back to the original, e.g. hexagonal. Of course this only works if the repetition maintains the symmetry, e.g. hexagonal nA=nB, or cubic nA=nB=nC.

Title: Re: K point setting in band structure calculation
Post by: jerry on September 28, 2012, 10:06

Thank you veru much. Recently, i have read an article which concentrates on the electronic structure of BN nanoribbons (built by substitute the carbon atoms of GNRs with boron and nitrogen atoms). In that paper they have calculated the transverse dipole moment of BNNR per unite cell, can you give me a script to do this using ATK?

Thanks a lot!