repetitions of dynamical matrix

[Mr sun]

Dear Sir,
I made the graphene phonon vibration mode, respectively, in the dynamical matrix set up repetitions (na = 7, nb = 7, nc = 1) and (na = 7, nb = 7, nc = 3), the results are different , Repetitions of the nc how to set up?or others?There is a script attached.Thank you very much.

[Anders Blom]

The differences should only be small numerical due to the different repetition values. If you make the cell larger in Z the difference should vanish completely.

In general, when making a comment or asking question involving the words "the results are different", you need to show the results, so we can also see the difference.

[Roc]

Dear Anders Blom,

From the scripts 771 and 773, I also obtain the different results, like the attachment. It seems that the 771 produces a strange results.  What's the matter?   

[Mr sun]

Dear Anders Blom,
I am learning PHYSICAL REVIEW B 93, 035414 (2016), debugging a lot of parameters are not the same results, and at http://quantumwise.com/about-us/quantumwise-news/item/1086-vnl-atk-2017 -released site on the dynamical matrix bug. Can you help with a DFT method to simulate PRB articles in the article graphene vibration mode script? thank you very much.

[Anders Blom]

From the scripts 771 and 773, I also obtain the different results, like the attachment. It seems that the 771 produces a strange results.  What's the matter?

Strange how? This is at k=0 so you have several degenerate modes at zero energy, and the ordering may differ in the two calculations due to tiny numerical differences. You cannot trust that "mode 1" is the same in both calculations, at this k-value. Besides, plotting phonon modes is better done at finite k, else the wavelength is infinite.

[Roc]

Thank you, Anders.   
While, could you share a script (or give an example) which models the vibrational model and Electron Phonon Coupling of  graphene by DFT method using 2017.0 version,  like the results FIG. 4 of PHYSICAL REVIEW B 93, 035414 (2016). 

[Jess Wellendorff]

We would certainly like to help you in reproducing that paper, but truth is we don not have the scripts you ask for in this and other Forum post. I suggest you contact the correpsonding author on the paper, Tue Gunst (tue.gunst@nanotech.dtu.dk)

Regards, Jess Wellendorff