Grephene and Mos2 Phonon vibration mode

[Mr sun]

Dear Sir,
I am learning physics reviews B 93,035414 (2016), according to the idea and parameters of the article, to simulate some of the examples in the article, but the results and the article is somewhat different .1.grephene LO and TO vibration mode and the article is quite different 2.Mos2 The TO2, LO2, ZO2 vibration modes are different. 3. Is the question raised about qA, qB, qC in dynamical matrix and Vibration Visualizer (should pay attention to those important parameters)? Or other questions?
How can i make my question more accurate? thank you very much

[Daniele Stradi]

Hi,

I think your calculations are correct. In the case of graphene, the two modes you visualize are linear combinations of the LO and TO normal modes. These two modes can form linear combinations since they are iso-energetic at the Gamma-point.

To obtain the "conventional" normal modes, shown in PRB 93, 035414 (2016), you simply have to modify the atomic positions of the graphene atoms as shown in the attached script. Calculating the phonons with this geometry will result in normal modes which are similar to those show in Fig. 4(c) and Fig. 4(d) of the paper.

Regards,
Daniele. 

[Mr sun]

Hi,
Thank you very much for your help, let me know more about this problem. But in accordance with your script when the implementation of the following problems. 1.graphene in the Vibration Visualizer TO mode needs to flip the unit cell position and PHYSICAL REVIEW B 93, 035414 (2016) in the FIG. 4. (d) consistent, this flip and the article described in the phonon vibration Is the pattern TO consistent? 2. In the simulation of Mos2, according to your ideas' these two models can form a linear combination, because they are equal at the Gamma point. ', In addition to the ZO2 model results are different, the other results are consistent, is not where the parameters set? see attached. 3. I have also learned how the electro-acoustic coupling energy, the Fermi speed, and the speed of sound are accurately calculated in the study of PHYSICAL REVIEW B 93, 035414 (2016), and whether there is a relevant script file sharing?

[Daniele Stradi]

As Jess Wellendorf mentioned in other forum posts, we would certainly like to help you in reproducing that paper, but truth is we don not have the scripts you ask for. I suggest you contact the correpsonding author on the paper, Tue Gunst (tue.gunst@nanotech.dtu.dk)

Regards,

Daniele.