Topics

1

General Questions and Answers / GaN sheet

« on: May 13, 2013, 12:46 »

Respected Sir,
I want to design a GaN sheet using ATK_VNL version 11.2.3? Please help me..
Actually we want to design a (11,0) GaN sheet, which can be further used for making GaN Nanotube of (11,0) tube index.. This sheet total energy is needed for calculating the strain energy of GaN NTs...

We have tried by replacing individual atoms of CNTs through Ga and N but its a very difficult and time taking proces.. and in fact for achieving a minimum energy configrations its too difficult.. Please suggest any simpler way...

With Highest Regards!

2

General Questions and Answers / Electronic bands

« on: May 13, 2013, 08:36 »

Respected Sir,
Thanks for your kind support..
In the previous query I have mentioned that the nanowires that I have studied are simple tetragonal type, Now my query is if I have a face cenetred cubic structure of Si bulk and using it I make a 1-D linear nanowire along z then what are the symmetry points that appears in its band structure. If it comes like GKXG then its right or wrong?

With Highest Regards!

3

General Questions and Answers / Stability analysis

« on: May 12, 2013, 14:16 »

Respected Sir,
In my calculation of 1-D Si nanowire in its different shapes such as linear, ladder, square, dumbbell, hexagonal etc. The zigzag nanowire of Si attains the lowest total energy amongst all and treated as the most stable one? So, does it imply that zigzag,ladder and square nanowires of Si are more stable than bulk Si? Can you please provide me the formula for calculating the cohesive energy of bulk structures using total energy of bulk.

The fact that zigzag nanowires of Si possess the highest binding energy which seems to suggest that it has the largest numbers of nearest neighbor (nn) atoms, among all the nanowires considered. But the fact is that it has only two atoms,whereas square and dumbbell nanowire structures look more closely packed in my case. There is not any kind of rearrangement occurring after relaxation, resulting in more number of nn in zigzag NWs compared to rest?
How on the basis of lowest total enery and highest binding energy I will strictly define the stability of Si zigzag as most stable structure? Without the discussion of nn (   As the number of nearest neighbours increase, the binding energy increase).

With Highest Regards!

4

General Questions and Answers / Band structure analysis

« on: May 11, 2013, 10:18 »

Respected Sir,
I have a band structure of 1D nanowire of lead  along Γ-X-Γ-K-X , but actually the wire is relaxed along Z. Then how I defend that the X that appear in between is simply a point in the Brillioun Zone along Z-direction. Is there any method for calculating the coordinates for the special points Z, X and K for tetragonal supercell.

With Highest Regards!

5

General Questions and Answers / Method used for the calculations

« on: May 11, 2013, 10:07 »

Respected Sir,
I have one urgent query regarding the method of the calcultions which ATK-VNL used, is it a PW method or LCAO method?Which pseudopotential ATK-VNL use? Is it a norm-conserving Pseudopotential? If yes, then tell me how this pseudopotential is better then ultrasoft pseudopotential.

With Highest Regards!