Messages

16

General Questions and Answers / Re: A warning about convergence when calculating transport properties

« on: August 1, 2011, 16:46 »

I have not tried the basis band structure calculation of MoS2 sheet, do you mean the sheet with the same dimension of the electrode? how to find the the appropriate k-points?

17

General Questions and Answers / Re: A warning about convergence when calculating transport properties

« on: August 1, 2011, 15:39 »

It seems there is no trend to converge even after 100 iterations, part of dH and dE after 100 is attached, and the basis set is double-zeta polarized.

18

General Questions and Answers / Negative current under positive bias

« on: August 1, 2011, 03:11 »

When I set the right electrode negative voltage(like -0.2, -0.4,-0.6), I got negative currents, but when the negative voltage change to -0.8, -1.0, the current is positive. What's wrong? Dose the phenomenon make any sense?

19

General Questions and Answers / Re: Calculation the transport properties of graphene

« on: July 23, 2011, 12:28 »

Thanks for your reference !

20

General Questions and Answers / Re: Calculation the transport properties of graphene

« on: July 22, 2011, 15:09 »

Sorry for making my comments unclear.
It seems you use the symmetry of energies of VB and CB as the standard to determine the validity of the k-sampling. So can we determine the validity of the k-sampling of other materials in the same way, I mean, also through the symmetry of the VB and CB at K point?

21

General Questions and Answers / Re: Calculation the transport properties of graphene

« on: July 20, 2011, 18:50 »

Thank you for your detail explanation, but I have some questions:

what is the parameter you calculate in the code? and 41 is not belong to the group of 3*odd, so the example you list can be consider a exception ?

And the symmetry of the parameters of VB and CB means for what? is the symmetry of the parameter you list can be a test of the right choice of the k point without doing the convergence study?

Another question is for other 2D material, For example, BN or monolayer MoS2, for these system how to determine the right k-samping? Is the rule still work?

22

General Questions and Answers / Re: how to calculate working function

« on: July 20, 2011, 18:23 »

The script can help me calculate the working function of metal, what if the case of other material like graphene nanoribbon or bulk MoS2?

23

General Questions and Answers / Re: Calculation the transport properties of graphene

« on: July 18, 2011, 04:47 »

Is that right that more k-point sampling in the self-consistent loop will be more time consuming,e.g. (9,9) will cost more time than (3,3) ?

And how to figure out what k-point sampling is better? Is it based on experience or is there any general rule that we can follow?

24

General Questions and Answers / Re: how to calculate working function

« on: July 17, 2011, 12:08 »

Thank you!

25

General Questions and Answers / Re: Calculation the transport properties of graphene

« on: July 17, 2011, 12:03 »

If a sampling of 9, 10, 11 will make a big difference, then according to which can we decide the right choice?
And I was a little confused with the k-point sampling in the basis set and the k-sampling in transmission spectrum, what is the difference between them, those two parameters have any relationship and why transmission spectrum don't need k in z axis, it seems we need more k-sampling for transmission spectrum and why? Just as mentioned by zh, in the example of Fe/MgO/Fe I found the k for calculatore is 6, 6,100 for x,y,z while in the transmission spectrum the k sampling is 30, 30 for kA and kB

26

General Questions and Answers / how to calculate working function

« on: July 17, 2011, 02:58 »

Can ATK calculate working function of a certain material?

27

General Questions and Answers / Re: caculation of bloch state

« on: May 25, 2011, 15:50 »

I did it once again, and found the result is the same as yours. I am wrong, sorry for making such mistake!

28

General Questions and Answers / Re: caculation of bloch state

« on: May 24, 2011, 13:20 »

Yes, I am sure... Maybe you can try with new version with unit cell of zGNR, it is quite fast

29

General Questions and Answers / Re: A question about optimization

« on: May 24, 2011, 13:18 »

Thanks sincerely for your answer!

30

General Questions and Answers / Re: caculation of bloch state

« on: May 24, 2011, 12:39 »

But the result I got from the non-spin-polarized one is that the edge states are localized on one edge of the ribbon for lowest conduction band while , for highest valence band, on other edge.