Topics

1

General Questions and Answers / scf failed

« on: October 20, 2011, 14:44 »

When I calculated a two probe system, the scf process failed.
 
At the beginning of the calculation, there was a warning:   The provided initial state parameter has no pre-calculated data.   Proceeding without setting an initial state.
And then, the density matrix calculation of the two electrode converged in 15 steps. But further calculation failed with a message "This application has requested the Runtime to terminate it in an unusual way.Please contact the application's support team for more information."

Can anybody meet with similar problems and how can you solve it?

2

General Questions and Answers / the I-V characteristics of graphene: zigzag vs armchair?

« on: September 26, 2011, 04:22 »

I wanna calculate the transport properties of graphene using atk 2008.10. Two kinds of unit cell were used to set up the two-probe system, which the z-direction of one was along with zigzag edges and that of the other one along with armchair edges. The structure of both two were infinite graphene.However, the I-V characteristics were totally different. I don't know why. Can anybody tell me the reason? Thank you.

3

General Questions and Answers / transmission eigenvalue and eigenstate

« on: February 24, 2011, 11:17 »

hello!
I have calculated the transmission eigenvalue and eigenstate of graphene ribbons recently. To my surprise,when one result showed the eigenvalue=0, the eigenstate distributed in the whole two-probe system without obvious break; in the contrast, when one result showed the eigenvalue =0.9, the eigenstate are blocked in the interface between the central scattering region and the left electrode. So i am confused what's the relationship between transmission eigenstate and eigenvalue.
by the way, the eigenstate was shown by the VNL nanoscope, i chose isosurface plot. And in my VNL, 'the absolute isovalue' could not be ticked. Would you like to  tell how can i choose this option? Does it need some other code.
Thanks very much!