[Wien] Ghost band error in SnS2 continued....

[shamik chakrabarti]

Dear Sir,

         I have started to optimize the structural parameter with non-local
vanderwaals functionals. However when I edit case.in0 to put
XC_GGA_X_B86_R EC_LDA VC_LDA, lapw0 error appeared with LIBXC not
installed. I am using wien2k 19.1. Is it that we have to install the XC
functional separately or whether I am doing something wrong?

Now, I am running the structure optimization with XC_PBESOL in case.in0.
Again whether am I doing something wrong?

with regards,

On Wed, 29 Jan 2020 at 11:01, shamik chakrabarti <shamik15041981 at gmail.com>
wrote:

> Dear Prof. Laurence, Prof. Gerhard & Prof. Peter,
>
>                                   Thank you so much for your valuable
> advices. I will try all the options & will let you know the results within
> a few days.
>
> with best regards,
>
> On Wed, 29 Jan 2020 at 00:59, Peter Blaha <pblaha at theochem.tuwien.ac.at>
> wrote:
>
>> First of all, the VASP gaps of bulk SnS2 are 1.91 eV, not 2.1 as you are
>> writing ?????
>>
>>
>> Then there are other VASP papers, which report different results, in
>> particular different structural parameters:
>>
>> (Phys. Chem. Chem. Phys., 2016, 18, 318)
>> a=3.693 c=11.680   gap:   1.91
>>
>> https://doi.org/10.1016/j.actamat.2014.03.042:
>> a = 3.518 Å, c = 5.844 Å),  gap 1.92 eV  (also PBE+U(9 eV !!
>>
>> SnS2 is a layered material and all VASP papers used a DFT-D2 (+U)
>> approach. It could be that your Sn position is quite different from
>> theirs ???
>>
>> PS: I would not reduce the RMTs. You will make the effect of U even
>> smaller with smaller RMTs.
>>
>> PPS:
>> I'd use TB-mBJ or hybrid-DFT for band gaps- but you said, band gaps are
>> not your focus, but the voltage of LiSnO2.
>>
>> For this you need good structural parameters AND good cohesive energies.
>>
>> I'd use a vdW-functional (for instance rev-vdW-DF2, see our paper) to
>> optimize the structure and also the SCAN meta-GGA for the energies (the
>> formation energy determines the Voltage).
>>
>>
>> On 1/28/20 3:11 PM, shamik chakrabarti wrote:
>> >
>> > Dear  Professor Laurence and wien2k users,
>> >
>> >                                        with reference to my earlier
>> mail
>> > on SnS2, I have checked the change in RMT (for avoiding Ghostband) with
>> > U and corresponding band gap. The details are as follows;
>> >
>> > U = 7 eV      RMT reduction 6%     Band gap = 1.460 eV
>> > U = 8 eV      RMT reduction 15%    Band gap= 1.475 eV
>> > U= 9 eV       RMT reduction 30%    Band gap = 1.512 eV
>> >
>> > I have not able to reproduce the band gap ~ 2.1 eV as computed
>> > earlier using Vasp (Phys. Chem. Chem. Phys., 2016, 18, 318). Also,
>> > whether 30% reduction of RMT  is acceptable???
>> >
>> > Looking forward to further guidance from you.
>> >
>> > with regards,
>> >
>> > --
>> > Dr. Shamik Chakrabarti
>> > Research Fellow
>> > Department of Physics
>> > Indian Institute of Technology Patna
>> > Bihta-801103
>> > Patna
>> > Bihar, India
>> >
>> > _______________________________________________
>> > Wien mailing list
>> > Wien at zeus.theochem.tuwien.ac.at
>> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> > SEARCH the MAILING-LIST at:
>> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>> >
>>
>> --
>>
>>                                        P.Blaha
>> --------------------------------------------------------------------------
>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
>> Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
>> WWW:   http://www.imc.tuwien.ac.at/TC_Blaha
>> --------------------------------------------------------------------------
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>>
>
>
> --
> Dr. Shamik Chakrabarti
> Research Fellow
> Department of Physics
> Indian Institute of Technology Patna
> Bihta-801103
> Patna
> Bihar, India
>


-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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