[Pw_forum] phonon instability

[Stefano Baroni]

On Aug 23, 2011, at 8:40 PM, bhabya sahoo wrote:

> sir

???

> i am calculating the phase transition of some carbides
> the transition from B1 to B2 transition occures at 130 gpa by enthalpy compparison 

OK

> but i am able to find phonon instability at 130 gpa for B1 structure

you mean, a phonon (which mode?) goes soft at the same pressure at which the enthalpies of the two phase coincide?

> but at the same time i am not able to find the dyanamic stability of B2 phase

???

> but it occures high pressure (more than130 gpa )

???

> is there any explanation for this ?

explanation for WHAT?

what are you talking about? may we expect a somewhat more well thought and articulate question?

> is there any relation of thermodyanamical unstability
> and dyanamical unstability simultaneously?

???

> answers are highly appriceted with some reson

well-thought and well documented questions questions would be even more appreciAted for any reAson ...

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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