Re: [Phonopy-users] [**SPAM?**] Re: [**SPAM?**] Re: phonon energy

[Shilendra K. S. <sh...@ii...>]

Dear Roginskii Eugene ,

Actually, I am studying lanthanide doped luminescent materials in which
host matrix should have low phonon energy to minimize non-radiative losses
(link herein).

http://pubs.rsc.org/-/content/articlepdf/2014/ta/c4ta04274c

On the theoretical bases I want to see which host matrix has low phonon
energy. As it is written in this paper NaYF4 has low phonon energy (ca.
360 cm-1). Such phonon energy I want to calculate for other matrix.


Thank You

Shilendra


> Hi,
> Your question is out of scope of PHONOPY. And truly saying I don't
> understand what does your phonon energy means, do I can't answer. I can
> only recall, that phonon is a quasi-particle which determined by energy
> (eigenvalue of dynamical matrix) and atomic displacements (eigenvector of
> dynamical matrix) both depends on k-vector. The number of phonons in the
> periodic structure depends on number of atoms in unit cell e.g. 3N. This
> set may include double and/or triple degenerate modes, due to symmetry
> selection rules. The maxima in DOS usually hard to explain unambiguously,
> some are due to high concentration of phonons in the energy region some
> due to crossing of phonon branches. It make scene after plotting of band
> structure.
>
> If you want to calculate Harmonic phonon energy you're better study
> PHONOPY formulations on thermodynamic properties
> https://atztogo.github.io/phonopy/formulation.html#thermodynamic-properties
>
> and run the calculations with proper setup. Below is example how to create
>  thermal_properties.yaml file:
> phonopy  --mp="41 41 41" -t --dim="2 2 2" --tmax=2004 --tstep=2  -c
> POSCAR
>
> Good luck,
> Eugene
>
>
> On 07/28/2017 04:28 PM, Shilendra Kumar Sharma wrote:
>
> Dear Roginskii Eugene thank you for your reply !
>
> I am using VASP+Phonopy for phonon calculation. As you suggested
> conversion factor for vasp.
>
> I gave command "phonopy -p --dos --factor=521.47 mesh.conf" for phonon
> DOS
> calculation. Now my frequencies are in cm-1.
>
> I have attached here my dos plot and from DOS plot maximum frequency will
> be my phonon energy which I am getting 250 cm-1.
>
> Am I understanding right ?
> If I am wrong, please correct me!
>
>
> Thank You
>
> Shilendra
>
>
>
>
>
>
>
>
> Hi, if you using VASP calculator use --factor=521.45 option. In case of
> ABINIT use --factor=716.851928469, the value calculates as multiply of
> factors:
> #Abinit_units to THZ= 21.4906801658
> #THZ to CM-1=33.356410
>
> On 07/28/2017 04:52 AM, Shilendra Kumar Sharma wrote:
>
>
> Dear All phonopy users,
>
> How does calculate phonon energy for any system in cm-1 ? I am doing
> phonon calculation with VASP+phonopy combination. I have calculated
> phonon
> DOS and band structure. Now I want to calculate phonon energy (cm-1) for
> my system. How can I know or calculate phonon energy for my compound
> from
> phonon calculation.
>
>
> Thank You All
>
> Shilendr
>
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