Re: [Phonopy-users] use phonopy-qha

[Dr. R. C. <ra...@ig...>]

Dear Dr Togo,

Thanks for the message.  But let me make sure that I got it correct.

At all volumes of e-v.dat, NO imaginary bands are expected.
Is this correct?

Thanks,
Ravi

On Tue, 2012-04-24 at 09:47 +0900, Atsushi Togo wrote:
> Hi,
> 
> The Helmholtz free energy implemented in phonopy is that defined for
> harmonic (or quasi-harmonic) frequencies. So if there are imaginary
> modes, it is not well treated. Therefore phonopy-qha gives wrong
> result. This problem may be overcome considering anharmonicity
> explicitly, but this is beyond the feature of phonopy.
> 
> Togo
> 
> On Mon, Apr 23, 2012 at 8:06 PM, Dr. Ravi Chinnappan <ra...@ig...> wrote:
> > Dear phonopy users,
> >
> > I am trying use to VASP-DFPT phonopy interface.
> >
> > The syntax:
> >
> > phonopy-qha e-v.dat thermal_properties-{1..10}.yaml
> >
> > It is stated in the manual that the list of "thermal_properties.yaml"
> > files corresponds to the respective volumes of e-v.dat file.
> >
> > The phonon spectrum corresponding to non-equilibrium volumes show
> > imaginary bands (which was not there for equilibrium volume).
> >
> > Whether the calculation is an error?  If so, how to get around this
> > error?
> >
> > Thanks,
> > Ravi
> >
> > --
> > Dr. Ravi Chinnappan <ra...@ig...>
> > Indira Gandhi Centre for Atomic Research
> >
> >
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> 
> 

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