Are the polar-phonon frequency and the effective longitudinal optical phonon the same thing ?
If not , how to calculate the effective longitudinal optical phonon?
Yes, the polar phonon frequency and the effective longitudinal optical phonon are the same thing. They are calculated using
when i calculate phonon-frequency ,it always come out wrong,
My calculations are always at 0.85Thz，when i calculate Ga2O3, but this results is obviously wrong. and i estimated it should more than 10Thz.
and ,there is a strange phenomenon here.
when i use primitive cell(20atom)it is 0.84Thz.but when i use supercell(80atom).it is 12.48Thz
this is coufusing me .
this is mt input about phonon-frequency
this is 20atom primitive cell
this is 180 atom supercell
It seems like the highest frequency in your primitive unit cell calculation is 1.42 THz. So its not clear how amset would ever calculate a phonon frequency > 10 THz.
- Make sure amset is the most recent version.
- Make sure your primitive cell calculation doesn’t have any errors.
thank you so much your reply.
but i also have a qurestion ,
for this material it"s pop_frequency always range from 8.44Thz to 11.60Thz.
but it’s 0.84Thz in the amset phonon-frequence. it make me confused .Can you answer this for me .
I’m afraid I don’t understand your question? Were you able to check your VASP calculation to ensure that the phonon frequencies were correct (i.e., they are giving frequencies in the correct range). Secondly, you should check you are using the latest amset version.
If you’re sure its an issue with amset you can upload the vasprun.xml and I will take a look.