Questions tagged [quasi-harmonic-approximation]

For questions regarding the quasi-harmonic-approximation.

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9 votes
1 answer
266 views

Is there an upper limit of temperature after which the quasi-harmonic approximation (QHA) fails?

I can't seem to articulate what made me ask this question but it sprang up when I asked: What does it mean to say a material is 'anharmonic'?. I've heard before that the electronic entropy ...
Hitanshu Sachania's user avatar
15 votes
2 answers
1k views

What does it mean to say a material is 'anharmonic'?

I understand that a harmonic picture of the potential in a material isn't enough to study lattice dynamics thoroughly. The quasi-harmonic approximation is a good workaround and helps incorporate ...
Hitanshu Sachania's user avatar
10 votes
0 answers
254 views

Phonon density of states as a function of frequency vs energy [closed]

Lattice dynamics codes like Phonopy output density of states, $g_{(\omega)}$, as a function of frequency. Since $\int g_{(\omega)}d\omega$ is the number of states ...
Hitanshu Sachania's user avatar
20 votes
1 answer
655 views

What do phonon dispersion (or lattice dynamics) studies include?

I use the codes phonopy and phonopy-qha for phonon dispersion studies. phonopy-qha gives ...
Hitanshu Sachania's user avatar