[Wien] Problems in convergence due to application of mBj potential

[Kateryna Foyevtsova]

No gap with high U reminds me the situation that I've observed in an
oxide with orbital degeneracy. Eventually, I had to lower the unit cell
symmetry to allow for some orbital order which also opened a gap at U
value adequate for that system.

So, maybe, that is the problem in your case too.

What system are you calculating?

Does is have degenerate orbital states at the Fermi level in a
non-spin-polarized calculation?

Do you do a ferromagnetic calculation?



On 22/08/12 04:48, Madhav Ghimire wrote:
> Dear wien users and developers,
>      I am working on some 3d TM oxides. With a normal scf cycle with or
> without inclusion of U value, I got good convergence in energy and
> charge. This oxide material is reported to have a bandgap of approx. 0.3
> eV. In GGA, I do not observe any gap. In the meantime even with very
> high value of U, the bandgap do not open up. Because of this, I tried to
> implement mBj potential  (in order to find the bandgap) both with and
> without inclusion of U, but the energy and charge do not converge.
> Rather even for a large number of iteration (199), the energy and charge
> remains constant without convergence (shown below).
> 
> For GGA without mBj the scf cycle smoothly converges as below:
> in cycle 22    ETEST: .0000236850000000   CTEST: .0038743
> in cycle 23    ETEST: .0000184300000000   CTEST: .0012996
> in cycle 24    ETEST: .0000174650000000   CTEST: .0006011
> in cycle 25    ETEST: .0000037600000000   CTEST: .0007451
> in cycle 26    ETEST: .0000016050000000   CTEST: .0001163
> 
>>   stop
> 
> while  with mBj+GGA, energy and charge convergence remains constant
> above cycle 103 and could not converge as below:
> in cycle 193    ETEST: .2112103950000000   CTEST: 2.0591251
> in cycle 194    ETEST: .2112103950000000   CTEST: 2.0591251
> in cycle 195    ETEST: .2112103950000000   CTEST: 2.0591251
> in cycle 196    ETEST: .2112103950000000   CTEST: 2.0591251
> in cycle 197    ETEST: .2112103950000000   CTEST: 2.0591251
> in cycle 198    ETEST: .2112103950000000   CTEST: 2.0591251
> in cycle 199    ETEST: .2112103950000000   CTEST: 2.0591251
> 
>>   energy in SCF NOT CONVERGED
> 
> Does anyone have experienced this type of problems. If so, please let me
> know how it can be converged. I followed all the steps as described in
> previous wien mail and userguid but could not solve.
> Your help to solve this issue will be higly appreciated.
> Thanks in advance
> 
> Madhav Ghimire
> 
> -- 
> MANA, National Institute for Materials Science (NIMS)
> 1-1 Namiki, Tsukuba, Ibaraki, Japan 
> Phone: +81-29-851-3354 (ex.4115)
> 
> 
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> 
> 
> 
> 
> -- 
> MANA, National Institute for Materials Science (NIMS)
> 1-1 Namiki, Tsukuba, Ibaraki, Japan 
> Phone: +81-29-851-3354 (ex.4115)
> 
> 
> 
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien