[QE-users] Is there any problem if I use less ecutwfc and ecutrho than the suggested value in the pp file?

[ENDALE ABEBE]

Dear Expertise

Let me say I am calculating the energy bandgap of a semiconductor, which
doesn't have reported value in literature.
What is the parameter that I need to check to say the ecutwfc/ecutrho is
sufficient and the value ot energy bandgap is correct?

Thank you for your support

With Best Regards


On Tue, Oct 13, 2020 at 1:06 AM Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:

> As long as your cutoffs are sufficiently good to get the desired accuracy
> on the targeted properties, there is no problem. The cutoffs suggested in
> the PP file are on the safe side and thus quite high, if I remember
> correctly.
>
> Paolo
>
> On Mon, Oct 12, 2020 at 2:56 PM ENDALE ABEBE <endtse at gmail.com> wrote:
>
>> Dear Expertise
>>
>> The suggested values of the ecutrho and ecutwfc are making my calculation
>> expensive. For instance, in the pseudo potential file of Bi,
>> Bi.pbe-dn-kjpaw_psl.1.0.0.UPF
>> <https://www.quantum-espresso.org/upf_files/Bi.pbe-dn-kjpaw_psl.1.0.0.UPF>,
>> these are:
>>
>>     Suggested minimum cutoff for wavefunctions:  45. Ry
>>     Suggested minimum cutoff for charge density: 455. Ry
>>
>> Is there any problem if I use less values than these as much as the total
>> energy of the system converges?
>>
>> Thank you in advance for your response.
>>
>> With Regards
>>
>> --
>> Endale Abebe
>> Program coordinator and Lecturer
>> Faculty of Materials Science and Engineering
>> Jimma Institute of Technology
>> Jimma University
>> P.O.Box 378, Jimma, Ethiopia
>> Mobile: +251921381598
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
>> users mailing list users at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
>
>
>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users



-- 
Endale Abebe
Program coordinator and Lecturer
Faculty of Materials Science and Engineering
Jimma Institute of Technology
Jimma University
P.O.Box 378, Jimma, Ethiopia
Mobile: +251921381598
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