[QE-users] 回复: Pw.x Cell_factor issue

[Guo, Mr Yiming (Bill) Guo]

Dear Dr. Lorenzo Paulatto,

Thank you for your reply.  I am working on three calculations,

The calculations involve:

  1.  A Nitrogen-doped graphene layer (VC-relax/SCF)
  2.  Li2S6 (VC-relax/SCF).
  3.  The combined system to determine the lowest energy state and calculate the binding energy of Li2S6 on the Nitrogen-doped graphene layer.

I have encountered an issue with the VC-relax cell_factor for the Nitrogen-doped graphene layer. When I change the cell factor to 3, the calculation proceeds without problems.

Given my limited experience with Quantum ESPRESSO (only 1.5 months), my approach has been to build the model first, perform structure optimization, and finally conduct the SCF calculation.

From my understanding, if the lattice parameters are unknown or need optimization, I should use VC-relax. However, if the lattice parameters are known and fixed, VC-relax is unnecessary.

Could you please confirm if this approach is correct and advise on how to properly set the cell factor for the Nitrogen-doped graphene layer? Any additional insights or recommendations you can provide would be greatly appreciated.

Thank you for your time and assistance.

I have attached the N-doepd graphene layer file as well.
[https://res.cdn.office.net/assets/mail/file-icon/png/generic_16x16.png]Li2S6 (2) 1.in<https://liveuclac-my.sharepoint.com/:u:/g/personal/ucecuof_ucl_ac_uk/ESnKgHLpoR5Iqv16PqG-9FkBvDMGUWgaD-zgnp8YoBK3VA>
[https://res.cdn.office.net/assets/mail/file-icon/png/generic_16x16.png]NG 1.in<https://liveuclac-my.sharepoint.com/:u:/g/personal/ucecuof_ucl_ac_uk/EZbXvMWIroZGkiYC_fayFpoBL4NU9_akxZoNgAQ4cmZW_A>


Best regards,
Bill Guo
________________________________
发件人: users <users-bounces at lists.quantum-espresso.org> 代表 Lorenzo Paulatto <lorenzo.paulatto at cnrs.fr>
发送时间: 2024年6月11日 16:23
收件人: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
主题: Re: [QE-users] Pw.x Cell_factor issue


⚠ Caution: External sender


Hello,

you are doing a variable cell relaxation, but your input is not a solid, hence the cell is collapsing.

Do not use vc-relax for molecules (or whatever weird object you are trying to simulate)

[cid:part1.2uDFKwi0.0vRQ18pH at cnrs.fr]

hth


On 11/06/2024 15:42, Guo, Mr Yiming (Bill) Guo wrote:
Dear Experts,

I hope this message finds you well.

I am currently performing a variable cell relaxation (vc-relax) calculation for Li2S6. However, I keep encountering the error message: "Not enough space allocated for radial FFT: try restarting with a larger cell_factor." According to the documentation, the recommended values for cell_factor during the pw.x execution are 2 or 1. Despite trying both values, the error persists. Interestingly, when I set cell_factor to 3, the calculation proceeds without any issues.

Could you please advise if setting the cell_factor to 3 is appropriate for pw.x, or if there might be an underlying issue with my parameters?

Thank you for your time and assistance.

Best regards,
Bill Guo



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