[QE-users] Absorption spectra for systems with unpaired electrons (Yang Liu)

[Yang Liu]

Dear Matthew

Thanks for your replies.

Actually, I'm not quite sure if this is a software issue or method issue.... I just followed the procedure of the TDDFT tutorial: SCF->turbo_lancsoz->spectrum. Turbo_lancsoz didn't handle spin-polarized SCF calculation,nor the calculation without gamma_only k point mesh. If I have some systems with unpaired electrons, how could I proceed with the calculation? That's what I was wondering.

Regards


-----------------------------------------
I asked Yang Ha, who just did a workshop on Orca, about this problem. Here's what he had to say:        mam
-------- Forwarded Message --------
Subject: Re: [QE-users] Absorption spectra for systems with unpaired electrons (Yang Liu)Date:   Fri, 13 Aug 2021 08:41:07 -0700
From:   Yang Ha <yan... at lbl.gov>
To:     Matthew Marcus <mamar... at lbl.gov>
Hi Matthew,
I am not too sure about what he means by systems with unpaired electrons. If he means open shell singlet, then it is not a software issue, but method issue. ORCA has the function to do so called Brokensym. However, the excitation state of O2 can be tricky, because there are two types of singlet oxygen. I actually posted a question on the ORCA forum a few years ago https://orcaforum.kofo.mpg.de/viewtopic.php?f=8&t=5923&p=25407#p25407 <https://orcaforum.kofo.mpg.de/viewtopic.php?f=8&t=5923&p=25407#p25407> That is why I raised the same question to Ali yesterday. The (Detla)SCF method could be a solution to that. He/she really should attend our workshop :)Yang
On Fri, Aug 13, 2021 at 8:19 AM Matthew Marcus <mamar... at lbl.gov <mailto:mamar... at lbl.gov>> wrote:    This question came through the Quantum Espresso forum.  Does Orca do
    TDDFT with unpaired electrons correctly?  If so, I could suggest it
    to him.
             mam
    -------- Forwarded Message --------
    Subject:        [QE-users] Absorption spectra for systems with unpaired
    electrons (Yang Liu)
    Date:   Fri, 13 Aug 2021 12:33:38 +0800
    From:   Yang Liu <rabbitkil... at 163.com <mailto:rabbitkil... at 163.com>>
    Reply-To:       Quantum ESPRESSO users Forum
    <users at lists.quantum-espresso.org
    <mailto:users at lists.quantum-espresso.org>>
    Organization:   FDU
    To:     users <users at lists.quantum-espresso.org
    <mailto:users at lists.quantum-espresso.org>>
    Dear all
    I am wondering if I can calculate the absorption spectra for systems
    with unpaired electrons, e.g. O2 molecule,  in QE. It seems that the
    TDDFT modules (both turbo_lanczos and turbo_davidson) do not handle
    spin-polarized calculations, the GWW module don't either.
    Could you please help me on this?
    Thanks & Regards
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