[Pw_forum] SCF calculations do not converge

[IYAD AL-QASIR]

Hello All,
I am trying to calculate the phonon dispersion relations and phonon density
of states of UO2.
Please find the attached files UO2.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 second  representation of the second mode
for q (-0.1666667   0.1666667  -0.1666667), the *scf **calculations do 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- 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
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