[Pw_forum] smearing and electronic temperture

[Stefano Baroni]

On May 6, 2012, at 8:19 AM, bhabya sahoo wrote:

> i want to find the dispersion curve at 300k how can be done

dispersion of what: electronic bands, or phonon bands?
I would be surprised if 300 K made any difference in any electronic bands. Kohn anomalies in phonon dispersions may instead depend sensitively on temperature

> because i have seen some paper related the value of electronic tempe. by using fermi dirac smearing
> is it possible in quantum espresso
> how can this be done?

I think that you can specify "fermi-dirac" as a value for "smearing" variable

> is there any physics of electronic temp and smearing value
> this is beacause many unstable phonon modes become stable by incrising smearing value
> what should be the calibaration of temp. and smearing in espresso

look for "kohn anomaly" in the index of any good text in solid-state physics, study the relevant chapter, and revert to us if you need any further assistance.

SB

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

La morale est une logique de l'action comme la logique est une morale de la pensée - Jean Piaget

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