<p dir="ltr">As a small addendum, you may also need to ensure that the fft size in lapw0 (via case.in0) is a multiple of 6 along a & b to preserve equivalence of atoms.</p>
<p dir="ltr">---<br>
Professor Laurence Marks<br>
Department of Materials Science and Engineering<br>
Northwestern University<br>
<a href="http://www.numis.northwestern.edu">http://www.numis.northwestern.edu</a><br>
Corrosion in 4D <a href="http://MURI4D.numis.northwestern.edu">http://MURI4D.numis.northwestern.edu</a><br>
Co-Editor, Acta Cryst A<br>
"Research is to see what everybody else has seen, and to think what nobody else has thought"<br>
Albert Szent-Gyorgi</p>
<div class="gmail_quote">On Dec 23, 2015 06:57, "Peter Blaha" <<a href="mailto:pblaha@theochem.tuwien.ac.at">pblaha@theochem.tuwien.ac.at</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">a) As expected, something is wrong with your structure.<br>
<br>
It should be a hexagonal lattice (H and not P) and the angle gamma<br>
should be 120 and not 60, and also the positions need to be changed then.<br>
<br>
With an "H" lattice, wien2k keeps the symmetry properly and is less<br>
affected by rounding errors.<br>
<br>
b) And secondly, you did not answer, how you got the "gap" (from<br>
scf-file, output1 or bandstructure or DOS ???)<br>
<br>
Forget DOS (there is a smearing parameter set by default !)<br>
<br>
when you use a H lattice and meshes which can be divided by 3 (because K<br>
has 1/3,1/3,0 coordinates and only with a mesh like 3 3 1, 6 6 1, 9 9<br>
1, ... the "K"-point is in the mesh), you can use :GAP from scf,<br>
otherwise NOT. (best is to use a mesh conpatible with 2 and 3, so 6,6,1<br>
or 12,12,1 ..., because this includes also the M point.<br>
<br>
<br>
<br>
On 12/23/2015 01:22 PM, Islam, Md F wrote:<br>
> Hi Prof Blaha,<br>
><br>
> Here is the structure I am using. I tried to be as precise as possible with position coordinates.<br>
> I think size of the vacuum is sufficiently large so that supercell-supercell interaction is negligible.<br>
> So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh there is a gap at the Fermi<br>
> level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, gap closes but DOS is not<br>
> zero at the Fermi level (about 0.001/eV). Please let me know if I am doing anything wrong with<br>
> this calculation.<br>
><br>
><br>
> Thanks,<br>
> Fhokrul<br>
><br>
><br>
> Graphene<br>
> P LATTICE,NONEQUIV.ATOMS: 2<br>
> MODE OF CALC=RELA unit=bohr<br>
> 4.647800 4.647800 30.000000 90.000000 90.000000 60.000000<br>
> ATOM -1: X=0.00000000 Y=0.00000000 Z=0.50000000<br>
> MULT= 1 ISPLIT= 8<br>
> C NPT= 781 R0=0.00010000 RMT= 1.3200 Z: 6.0<br>
> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<br>
> 0.0000000 1.0000000 0.0000000<br>
> 0.0000000 0.0000000 1.0000000<br>
> ATOM -2: X=0.66666667 Y=0.66666667 Z=0.50000000<br>
> MULT= 1 ISPLIT= 8<br>
> C NPT= 781 R0=0.00010000 RMT= 1.3200 Z: 6.0<br>
> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<br>
> 0.0000000 1.0000000 0.0000000<br>
> 0.0000000 0.0000000 1.0000000<br>
> 12 NUMBER OF SYMMETRY OPERATIONS<br>
> -1-1 0 0.00000000<br>
> 0 1 0 0.00000000<br>
> 0 0-1 0.00000000<br>
> 1<br>
> -1-1 0 0.00000000<br>
> 0 1 0 0.00000000<br>
> 0 0 1 0.00000000<br>
> 2<br>
> -1-1 0 0.00000000<br>
> 1 0 0 0.00000000<br>
> 0 0-1 0.00000000<br>
> 3<br>
> -1-1 0 0.00000000<br>
> 1 0 0 0.00000000<br>
> 0 0 1 0.00000000<br>
> 4<br>
> 0 1 0 0.00000000<br>
> -1-1 0 0.00000000<br>
> 0 0-1 0.00000000<br>
> 5<br>
> 0 1 0 0.00000000<br>
> -1-1 0 0.00000000<br>
> 0 0 1 0.00000000<br>
> 6<br>
> 0 1 0 0.00000000<br>
> 1 0 0 0.00000000<br>
> 0 0-1 0.00000000<br>
> 7<br>
> 0 1 0 0.00000000<br>
> 1 0 0 0.00000000<br>
> 0 0 1 0.00000000<br>
> 8<br>
> 1 0 0 0.00000000<br>
> -1-1 0 0.00000000<br>
> 0 0-1 0.00000000<br>
> 9<br>
> 1 0 0 0.00000000<br>
> -1-1 0 0.00000000<br>
> 0 0 1 0.00000000<br>
> 10<br>
> 1 0 0 0.00000000<br>
> 0 1 0 0.00000000<br>
> 0 0-1 0.00000000<br>
> 11<br>
> 1 0 0 0.00000000<br>
> 0 1 0 0.00000000<br>
> 0 0 1 0.00000000<br>
> 12<br>
><br>
><br>
><br>
><br>
> ________________________________________<br>
> From: <a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a> [<a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a>] On Behalf Of Peter Blaha [<a href="mailto:pblaha@theochem.tuwien.ac.at">pblaha@theochem.tuwien.ac.at</a>]<br>
> Sent: Tuesday, December 22, 2015 3:29 PM<br>
> To: A Mailing list for WIEN2k users<br>
> Subject: Re: [Wien] Graphene bandstructure<br>
><br>
> The two eigenvalues at K must be identical by symmetry.<br>
><br>
> If you have a splitting of some meV it means that your structure is<br>
> slightly wrong.<br>
><br>
> Typical errors: positions of 1/3 and 2/3 must be given in full precision.<br>
> 0.3333 is NOT 1/3<br>
><br>
> Am 22.12.2015 um 20:31 schrieb Islam, Md F:<br>
>> Hi Prof Blaha,<br>
>><br>
>> I have got the gap from plotting bandstructure as well as DOS calculations.<br>
>> I can see the linear dispersion at the K point just like the way it is suppose to be<br>
>> when I plot all the bands in eV range. But if I zoom in at the K point in meV range,<br>
>> I can see the gap.<br>
>><br>
>> I don't think there is anything wrong with the structure. I did check all bond lengths,<br>
>> angles before I ran the calculations and they are correct. I suspect I may have to adjust<br>
>> parameters. I started to see some difference with LDA xc functional with larger k mesh.<br>
>><br>
>><br>
>> Thanks,<br>
>> Fhokrul<br>
>><br>
>><br>
>><br>
>><br>
>> ________________________________________<br>
>> From: <a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a> [<a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a>] On Behalf Of Peter Blaha [<a href="mailto:pblaha@theochem.tuwien.ac.at">pblaha@theochem.tuwien.ac.at</a>]<br>
>> Sent: Tuesday, December 22, 2015 11:35 AM<br>
>> To: A Mailing list for WIEN2k users<br>
>> Subject: Re: [Wien] Graphene bandstructure<br>
>><br>
>> Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at<br>
>> the K-point and bands cross with a linear dispersion.<br>
>><br>
>> From where do you know that graphene has a gap in your calculations ??<br>
>><br>
>> From :gap in the scf file or from plotting the bandstructure or ...<br>
>><br>
>> It the state at K is not degenerate, you have the wrong symmetry and are<br>
>> not doing graphene.<br>
>><br>
>> Am 22.12.2015 um 16:51 schrieb Islam, Md F:<br>
>>> Hi,<br>
>>><br>
>>> I am trying to do a bandstructure calculation of graphene to check if I can<br>
>>> reproduce results discussed in literature (I am using a unit cell of 2 atoms).<br>
>>> With spin-orbit coupling, there should be a gap of the order of few micro-eV<br>
>>> and without spin-orbit, there should not be any gap at Dirac point. But I am<br>
>>> getting a gap of meV even without spin-orbit. I tried both GGA and LDA with<br>
>>> very dense mesh but the gap does not close. So I am wondering if anyone<br>
>>> have any suggestion about how to do it in Wien2k.<br>
>>><br>
>>><br>
>>> Thanks,<br>
>>> Fhokrul<br>
>>> _______________________________________________<br>
>>> Wien mailing list<br>
>>> <a href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br>
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>>><br>
>><br>
>> --<br>
>> --------------------------------------------------------------------------<br>
>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>
>> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982<br>
>> Email: <a href="mailto:blaha@theochem.tuwien.ac.at">blaha@theochem.tuwien.ac.at</a> WIEN2k: <a href="http://www.wien2k.at" rel="noreferrer" target="_blank">http://www.wien2k.at</a><br>
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>><br>
><br>
> --<br>
> --------------------------------------------------------------------------<br>
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>
> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982<br>
> Email: <a href="mailto:blaha@theochem.tuwien.ac.at">blaha@theochem.tuwien.ac.at</a> WIEN2k: <a href="http://www.wien2k.at" rel="noreferrer" target="_blank">http://www.wien2k.at</a><br>
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<br>
--<br>
<br>
P.Blaha<br>
--------------------------------------------------------------------------<br>
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982<br>
Email: <a href="mailto:blaha@theochem.tuwien.ac.at">blaha@theochem.tuwien.ac.at</a> WIEN2k: <a href="http://www.wien2k.at" rel="noreferrer" target="_blank">http://www.wien2k.at</a><br>
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</blockquote></div>