Phonon dispersions at high temperature

[ilukacevic]

Dear colleagues,

I would like to study cubic ZrO2 (insulator) phonon dispersions at high temperatures. It is known that this phase is stable against temperature (from melting temp.) until it lowers to 2370C. Then it goes a phase transition to a tetragonal phase.

When one does a T=0K rf phonon calculation of ZrO2 in cubic phase, one obtains an unstable TO phonon mode (the one which is responsible for the phase transition). But if one should do a rf phonon calc. at temperatures above around 2370C and above, this mode should be stable, i.e. all phonon modes should have real frequencies.

Thus, I would like to know if it is possible to conduct these calculations - rf phonon dispersions at these temperatures - and how?

Thank you all in advance!

Yours,
Igor Lukacevic

[mverstra]

There is a clever technique due to Souvatzis et al. (PRL 100 095901), and this is being implemented in abinit. It doesn't work yet, unfortunately. Almost there.

Matthieu

[mverstra]

PS : I think Souvatzis even did high T ZrO2 in some recent paper...

[ilukacevic]

Dear prof. Verstraete,

thank You for the reference. I think I found the Souvatzis' article from 2008 on ZrO2. Unfortunately, I don't have an access to APS journal articles, so I cannot find out what they did.

Yours,
Igor Lukacevic