[Wien] confusion regarding band structure of Graphene
xavier rocquefelte
xavier.rocquefelte at univ-rennes1.fr
Fri Dec 30 16:30:51 CET 2022
One more point the negative electrode is usually graphite and not graphene.
To estimate a voltage you need a positive electrode.
Estimating the voltage implies to properly treat not only the negative
but the positive electrode materials and with the same functional.
Best regards
Xavier
On 30/12/2022 16:26, xavier rocquefelte wrote:
>
> Dear Shamik
>
> I certainly did not follow all the discussion but it seems to me that
> your objective is reachable if you properly define your parameters.
>
> You mention that the band structure is finally not the essential point
> and you want to have a proper estimation of the voltage.
>
> Here are two well-known problems:
>
> - Li batteries voltage estimation is usually wrong and corrections
> must be applied (depending on the functional). I recommend the
> publications of Ceder's group.
>
> - The choice of the functional may be crucial and for carbon GGA is
> sometimes not the best.
>
> I will thus recommend first to choose your functional by estimating
> properly the band structure of the hexagonal cell of graphene and only
> after switch to the monoclinic cell to estimate the voltage.
>
> Best regards
>
> Xavier
>
> On 30/12/2022 15:51, shamik chakrabarti wrote:
>> Dear Prof. Blaha,
>>
>> I think the structure as used by me & as can be
>> used by downloading Graphene CIF file from material project database
>> are same with different representation. I have checked the XRD of
>> both the structures in VESTA & they are providing the same XRD
>> pattern for both the structures. In this regard lithiation voltage
>> for both the cases should be same. However the bandstructures need
>> special k points which is available for hexagonal lattice & not for
>> this monoclinic lattice. However, if the voltage is accurate I will
>> not bother for the band structure.
>>
>> with kind regards,
>>
>> On Fri, 30 Dec 2022 at 19:08, shamik chakrabarti
>> <shamik15041981 at gmail.com> wrote:
>>
>> Specially if I want LiC6 unit cell?...
>>
>> On Fri, Dec 30, 2022, 18:47 shamik chakrabarti
>> <shamik15041981 at gmail.com> wrote:
>>
>> Dear Prof. Blaha,
>> . . . . . . Thank you for your reply Sir. I have a
>> very dumb question. Whether the voltage simulated by this
>> attached structure will provide the same as will be provided
>> by the single unit cell?
>>
>> With kind regards,
>>
>> On Fri, Dec 30, 2022, 18:03 Peter Blaha
>> <peter.blaha at tuwien.ac.at> wrote:
>>
>> This is not the smallest unit cell of graphene but a 3
>> times larger
>> monoclinic cell.
>>
>> Start with graphite, remove the atoms at the second
>> z=0.75 layer and
>> eventually add some vacuum along z.
>>
>>
>> Am 29.12.2022 um 18:34 schrieb shamik chakrabarti:
>> > The structure of monolayer Graphenbe as I have used is
>> attached for your
>> > reference.
>> >
>> > On Thu, 29 Dec 2022 at 18:32, shamik chakrabarti
>> > <shamik15041981 at gmail.com
>> <mailto:shamik15041981 at gmail.com>> wrote:
>> >
>> > Dear Wien2k users,
>> >
>> > I have simulated a
>> structure of Graphene
>> > monolayer with primitive cell. I am getting DOS &
>> voltage
>> > accurately. However, while plotting band structure
>> I am facing a
>> > problem. In hexagonal Graphene the band structure
>> can be obtained
>> > with Gamma-M-K-Gamma, where K is the dirac point.
>> However, in my
>> > primitive cell I am getting a Brillouin Zone of
>> reciprocal lattice &
>> > not able to detect the Dirac point.
>> >
>> > The purpose of taking a primitive cell of monolayer
>> Graphene lies on
>> > the fact that I need control over all the C atoms.
>> >
>> > Looking forward to hearing from you.
>> >
>> > --
>> > 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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>> --
>> --------------------------------------------------------------------------
>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna,
>> A-1060 Vienna
>> Phone: +43-1-58801-165300
>> Email: peter.blaha at tuwien.ac.at WIEN2k:
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>>
>>
>> --
>> Dr. Shamik Chakrabarti
>> Research Fellow
>> Department of Physics
>> Indian Institute of Technology Patna
>> Bihta-801103
>> Patna
>> Bihar, India
>>
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> --
> ------------------------
> Professeur des Universités de Rennes 1
> Institut des Sciences Chimiques de Rennes (ISCR)
> Univ Rennes - CNRS - UMR6226, France
> https://iscr.univ-rennes1.fr/xavier-rocquefelte
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--
------------------------
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Institut des Sciences Chimiques de Rennes (ISCR)
Univ Rennes - CNRS - UMR6226, France
https://iscr.univ-rennes1.fr/xavier-rocquefelte
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