Messages

1

General Questions and Answers / Re: Young’s modulus of graphene

« on: August 3, 2017, 15:43 »

  Dear Peter,
 I want to know which method is correct, how to calculate the Young’s modulus of a 2D material？

2

General Questions and Answers / Young’s modulus of graphene

« on: August 3, 2017, 13:54 »

like
Recently, I am studying the script of Young's modulus of Umberto Martinez's graphene at the site "https://quantumwise.com/forum/index.php?topic=4717.msg20438#msg20438" (see above). By running Umberto Martinez's script I got a value of 1.371TGpa for a Young's modulus of graphene. And I use my own script (see attachment), the script's elastic_constant module to get another graphene Young's modulus (see Figure 1). Which one is correct?

3

General Questions and Answers / Re: The interaction energy of bulk electron-phonon coupling

« on: August 2, 2017, 16:30 »

Dear Troels Markussen,
Thank you for your guidance, I have a problem. According to PHYSICAL REVIEW B 93, 035414 (2016), can we share the scattering and inverse life-time of Fig. 7b and the computational script of Fig. 7c and d?thank you very much.

4

General Questions and Answers / Re: Different displacements can result in different phonon vibration modes

« on: August 2, 2017, 14:42 »

This is the script for the corresponding image of graphene above (see attached).

5

General Questions and Answers / The interaction energy of bulk electron-phonon coupling

« on: August 2, 2017, 13:03 »

Hi,
1. How to obtain the interaction energy (300 meV) of the electron-phonon coupling of graphene from PHYSICAL REVIEW B 93, 035414 (2016)?
2. From the PHYSICAL REVIEW B 93, 035414 (2016), how to obtain the Fermi velocities (0.9 *10 ^ 6 m / s) and the sound velocities of the graphene (sound velocities of 20.4 (12.6) * 10 ^ 3 m / s for The LA (TA) mode of graphene), can there be some specific clear script to share?Or whether there are other specific processes that make my answer to the question clearer?thank you very much.

6

General Questions and Answers / Different displacements can result in different phonon vibration modes

« on: August 2, 2017, 12:00 »

Dear sir,
After I learned the PHYSICAL REVIEW B 93,035414 (2016) article.Use ATK software to simulate the results of the article, found that set dynamical_matrix parameter "processes_per_displacement =" 1 or 2, resulting in different phonon vibration mode (such as the picture), what is the basis of this parameter settings? What is the reason for this result? thank you very much

7

General Questions and Answers / Re: repetitions of dynamical matrix

« on: August 2, 2017, 03:24 »

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.

8

General Questions and Answers / repetitions of dynamical matrix

« on: August 1, 2017, 17:37 »

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.

9

General Questions and Answers / The phonon vibration mode of graphene is different in Linux and Windows results？

« on: August 1, 2017, 16:58 »

Dear Sir,
I am learning PHYSICAL REVIEW B 93, 035414 (2016), according to the idea and parameters of the article, graphene phonon vibration mode in Linux and Windows in the implementation of the results are inconsistent (with a script) is not really the case , Or my script wrong? I hope that I can understand the answer to this question more clearly.

10

General Questions and Answers / Re: Grephene and Mos2 Phonon vibration mode

« on: August 1, 2017, 16:21 »

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?

11

General Questions and Answers / Grephene and Mos2 Phonon vibration mode

« on: August 1, 2017, 03:27 »

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