[Pw_forum] problem on phonon

[bhabya sahoo]

i am using quantum espresso static calculation obeys thermdyanamic stability
transition from B1 to B2 transition at 138 gpa  so ihave used 24 24 24
kpoint grid  for phonon in B2 phase is calculated 4 4 4 grid by linear
response calculation but why the instability (negative frequency in phonon )
upto 450 gpa  i have used pbe psudo potentials also the lattice constant is
exact for experimental data
 can metastability have negative frequency so why this occures
optimisation is ok
other problem why free energy is not coming for unstable phase for qha code
in quantum espresso
replay immidiate if u have solution
On Sat, May 28, 2011 at 5:38 PM, bhabya sahoo <bdslipun at gmail.com> wrote:

> sir
> i  used to calculate the phonon calculation on a 4*4*4 grid in cscl phase
> but the unstability persists upto 500 gpa
> but it is the thermodyanamic stability after 140 gpa  kpoints 24*24*24
> what may be reseon i donot know
> please help me
>
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