[Pw_forum] About ZnO Slab

[reza vatan]

Hi Bipul,

Just a question, How do you use 20 Angstrom vacuum in your calculation?

Best,
Reza

On Fri, May 8, 2015 at 3:43 AM, Bipul Rakshit <bipulrr at gmail.com> wrote:

> Thanks Giuseppe for your reply.
> Yes I do agree that there is a large dipole. But I also tried to apply the
> dipole correction (input attached ), but still it is not converging. This
> time I am using 20 Angstrom vacuum. But still its not converging.
>
> On Fri, May 8, 2015 at 2:23 PM, Giuseppe Mattioli <
> giuseppe.mattioli at ism.cnr.it> wrote:
>
>>
>> Dear Bipul
>> I've tried to run your input file, and I suppose that your calculation
>> does not converge because of the strong vertical dipole related to the 0001
>> wurtzite slab, which you could try to visualize by calculating the planar
>> average of the KS potential. My suggestion is to increase the vacuum to
>> decouple the images, but it could be not sufficient, because the dipole
>> should be quite strong. This is also a good reason for strange work-function
>> numbers. AFAIK the polar ZnO surfaces are rarely exposed in real systems.
>> The most stable and common surface is the nonpolar (10-10) one, which does
>> not usually show any convergence problem. Buy you know what surface you
>> need...
>> HTH
>> Giuseppe
>>
>> On Friday, May 08, 2015 12:29:25 AM Bipul Rakshit wrote:
>> > Dear users,
>> > I am doing ZnO slab calculation with 12 Double layer of ZnO. Since ZnO
>> is a
>> > wide band-gap material, so I am using occupation=fixed. I attached my
>> input
>> > also.
>> > But why the calculation is not converging?
>> >
>> > But when I am using occupation=smearing, it do converge. But it gives a
>> > work function of 3.47 eV after applying the dipole correction.
>> >
>> > So what mistake I am doing?
>> >
>> > Please help me in this regards
>>
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>
>
>
> --
> Dr. Bipul Rakshit
> Research Associate,
> Institute of Physics (IOP),
> Bhubaneswar- 751 005
> Orissa
> India
>
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