[Pw_forum] Phonon calculations

[Seyed Mojtaba Rezaei Sani]

Dear IYAD I. AL-QASIR

1. Reduce the alpha_mix(1) by default 0.7, e.g. to 0.4.
2. If it doesn't work, open PH/phcom.f90 and change
  INTEGER, PARAMETER :: maxter = 100
to something larger. ***Then recompile the
code***.

On Wed, Nov 23, 2011 at 7:39 PM, IYAD AL-QASIR <iyad.ne at gmail.com> wrote:

> Hello,
> I am trying to calculate the phonon dispersion relations and phonon
> density of states of UO2.
> Please find the attached filesUO2.scf.in and UO2.ph.in
>
> The calculations assume GGA and include spin-polarized effects.
>
> There are 6 representations and nine modes. The problem I have is: When I
> run the input file UO2.ph.in, *the scf calculation* for the  the second
> representation of the second mode for q (-0.1666667   0.1666667  -0.1666667)
> * is not converge.*
>
> Notes:
> 1- My runs assume UO2  is metallic, in fact UO2 is insulator with band gap
> of 2eV.( However, when I do the calculations using the VASP code I got very
> good result only by including the polarization effects)
> 2- In order to account for the band gap, one should implement the Hubbard
> term (LDA/GGA+U)
> 3- I tried different occupations  (smearing, tetrahedra)
> 4- I tried different starting_magnetization= 0.5, 1.0
> 5- I treid different mixing_betas (0.7, 0.35 )
> 5- the lattice parameter a= 10.285, is based on optimizing the structure
> and including spin-polarization effects.
>
>
> Any adivce to overcome this problem is highly welcomed.
>
> Kindest Regards,
> ______________________________
> aIYAD I. AL-QASIR, PhD
> Research Associate
>
> Department of Nuclear Engineering
> North Carolina State University
> Campus Box 7909
> 2500 Stinson Dr.
> Raleigh, NC 27695-7909
>
>
>
> --
> _______________________________
> IYAD I. AL-QASIR, PhD
> Research Associate
>
> Department of Nuclear Engineering
> North Carolina State University
> Campus Box 7909
> 2500 Stinson Dr.
> Raleigh, NC 27695-7909
>
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>
>


-- 
==========================================
Seyed Mojtaba Rezaei Sani
Computational Materials Science Research Lab
Physics Department, Isfahan University of Technology
84156-83111 Isfahan, Iran
Tel lab: +98 311 391 3731
Group page: http://cmsgroup.iut.ac.ir/
s.rezaeisani at ph.iut.ac.ir
===========================================
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