Dear Sandhya,

To calculate the phonon frequencies by using VASP, there are two ways :

**)The first one is to calculate only the frequencies at the \Gamma point, in this case you need to do a simple vasp calculation by using this command IBRION=5.

**) The second method is to calculate the frequencies along the Brillouin zone, in this case you have to use for example the Phonopy code which uses the Hellmann-Feynman forces from VASP, It is easy to use and it is an open source package of phonon calculations based on the supercell approach.

best

Thank yo Debbichi Lamjed....I will try second one. How to get accurate Hellmann-Feynmann forces?

You should take a look at the Phnopy website, http://phonopy.sourceforge.net/

There is the version to download, some example and a mailing list.

With Phonopy there are two methods to calculate the phonon frequencies: supercell method or DFPT method.

I advise the last one it's easy but it's a time-consuming method.

best

Thank you Debbichi Lamjed

Any good literature on phonon calculation and its basic theory for beginners.

Shilendra

Hello Debbichi Lamjed , I have used simple vasp calculation to get phonon frequency by using the command IBRION=5(the first method as you mentioned above). I get the frequency in OUTCAR file but I am not able to plot the Phonon DOS.Please help me how can I plot the DOS and Band.thanks in advance .

For the band and DOS you have to adopt 2nd method, 1st one it to only check phonon pn gamma point only. Surasree Sadhukhan

Then If the phonon frequency( at gamma point ) is positive then the structure is stable .Is this correct?

Is there any other way to get Phonon DOS without using Phonopy?

Surasree Sadhukhan, did you already find an answer? Phonon at Gamma can be different than when using the whole brillouin zone. As mentioned, there are two methods; supercell approach and DFPT. If you don't want to use Phonopy, you can try Phonon (DFPT approach) which comes with the QE package. For supercell approach, you can use SIESTA or Crystal. The latter is a good code to get phonon frequencies. Nevertheless, all these alternatives are slower, especially QE in comparison with VASP+Phonopy.

I hope it helps.

Best,

Dear all,

Can you help me in plotting the phonon density of states.?

I am using phonopy. I'm done with the files created by phonopy, Band structure, but not able to find any way to plot phonon density of states.

Thankyou in advance !