Messages

16

General Questions and Answers / Re: Fermi velocity in zigzag graphene nanoribbon

« on: May 14, 2020, 11:51 »

Thanks for your response
Here I am attaching the reference paper
https://doi.org/10.1016/j.commatsci.2017.09.050
I want to calculate quantum capacitance using the equation given in this reference paper. for which I required fermi velocity.


Thanks & Regards
Sonal

17

General Questions and Answers / Re: Brillouin zone in bandstructure of graphene nanosheet

« on: May 14, 2020, 11:34 »

Dear sir, Thankyou  for help

sir, I have increased the interlayer separation to  angstrong in both nanosheet and hexagonal sheet. After increasing separation, I have got exact bandgap for the hexagonal sheet, however in the case of nanosheet increasing separation doesn't give zero bandgap in nanosheet. I have calculated bandstruture for both G, Z  and G, Y BZ points.
here I am attaching the python file and bandstructure for G, Z, and G, Y Brillouin zone.
 in the G, Y direction I am getting the very high bandgap of 2.03ev. while in the G, z direction bandgap of 0.07ev
please help me out .

18

General Questions and Answers / Re: Brillouin zone in bandstructure of graphene nanosheet

« on: May 14, 2020, 09:54 »

Thankyou for your reponse
Related log files and Python files are attached herewith please find the attachments.

19

General Questions and Answers / Re: Fermi velocity in zigzag graphene nanoribbon

« on: May 14, 2020, 09:41 »

Thanks for your reply
Sir, I want to calculate the quantum capacitance of the system for which I need fermi velocity. How can we calculate the total fermi velocity of the system using the calculate velocity function?


Thanks & Regards
sonal

20

General Questions and Answers / Re: Fermi velocity in zigzag graphene nanoribbon

« on: May 13, 2020, 13:04 »

Dear sir, how can we identify which point should be used for calculating the Fermi velocity. In the pristine graphene case as given in the tutorial K point is selected because of Dirac cone available at that point. In other structure which having bandgap or having more than one band crossed the Fermi level in that case which point should we consider for calculating the Fermi velocity.

Please help me out, sir.
 Thanks & Regards
sonal

21

General Questions and Answers / Differene between zero bias conductance in bulk mode and device mode

« on: May 13, 2020, 12:51 »

Dear sir,
I have calculated Zero bias conductance of graphene nanosheet in bulk mode and in device mode there is huge difference between conductance. Can you please tell me why this difference is appearing in conductances.


Please help me out
Thanks in advance

22

General Questions and Answers / Brillouin zone in bandstructure of graphene nanosheet

« on: May 13, 2020, 12:42 »

Dear sir,
I have build a graphene nanosheet in ATK-VNL,  when I am calculating the band structure of nanosheet than the Brillouin zone point appear by default are only G, Z and bandstructure having bandgap of 0.02eV.  While In the hexagonal graphene sheet dirac cone with zero band gap is present at K point of brillouin zone but in the nanosheet which build from builder directly. I have explored the literature and have not found any paper which reported the electronic properties of retangular nanosheet.
1. Is there any difference in electronic properties of the hexagonal and unit cell or rectangular  shaped graphene sheet are they dependent on the supercell or i did something wrong.
2. brillouin zone point G, Z are for one dimensional material or it can also be used for Two dimensional material. I mean from the bandstructure how can we identify that this is the bandstructure of two-dimensional material or one dimensional material in case of unit cell.
For example graphene nanoribbon and nanosheet both have brillouin zoner point G, Z how can we differentiate both bandstructure.


Thanks in Advance

23

General Questions and Answers / errore in device optimization by extended huckle

« on: October 22, 2019, 14:41 »

Dear sir, I am facing issue in device optimization by extended huckle. there was an erroe msg that no pair potential are given. and also shows error in python file in optimization by LBFGS optimizer. is LBFGS optimizer is not supported by extended huckle or there is any error in my softwares potential files.

24

General Questions and Answers / Re: how to build phospherene nanoribbon in atkvnl with hydrogen passiviated edge

« on: October 2, 2019, 10:02 »

Thanks sir, I will try it.
and my ATKVNL version is 2016.4 by mistake i have written 20.16.03

25

General Questions and Answers / Re: how to build phospherene nanoribbon in atkvnl with hydrogen passiviated edge

« on: September 30, 2019, 16:07 »

where i can find this option

26

General Questions and Answers / how to build phospherene nanoribbon in atkvnl with hydrogen passiviated edge

« on: September 28, 2019, 06:15 »

Dear sir, I am facing issue with the builder in building phosphorene nanoribbon with hydrogen passivated edge, when I built phosphorene nanoribbon in 2016.03 version with builder plugin tool I have got all phosphorous hydrogen passivated. after deleting all hydrogens  except at edges and  after introducing buckling we have optimized the structure. Further that after the optimization we found that the geometry is not proper it is breaked. sir please help me out from this problem. I want to build blue and black phosphorene nanoribbon. 



Thanks

27

General Questions and Answers / Re: how to identify that which point should be used for calculating fermi velocity

« on: May 2, 2019, 07:01 »

Any one please help me out

28

General Questions and Answers / how to identify that which point should be used for calculating fermi velocity

« on: April 25, 2019, 14:33 »

sir, i want to know that how to identify which point G or Z should be considered for calculating fermi velocity when there is a band gap in silicene and germanene nanoribbon and in case of zero band gap which band index is considered for calculating Fermi velocity. In tutorial https://docs.quantumwise.com/manuals/Types/calculateVelocity/calculateVelocity.html  you have considered band index 3 but at dirac point there is band 3 and band 4 also i an little bit confused about this
please help me out.


Thanks