[QE-users] asr in dynmat.x

Thu Jun 8 11:22:39 CEST 2023

Dear Juliana,

Indeed the ASR in the old QE version did not include the correct rotational invariants for 2D systems, i.e. you should have 4 acoustic modes at Gamma that are zero.

Although, having a closer look to your inputs, I would suggest you to pay attention to:
1. Why have you commented out ‘assume_isolated’? That is usually important to get rid of the long-range planar interaction between images.
2. The threshold for phonons seem a bit too low. Did you do some tests? In my experience that threshold should be much lower, e.g. 1e-16/18.

HTH,
Lorenzo

********************************
Lorenzo Bastonero

PhD Student
U Bremen Excellence Chair,
Bremen Center for Computational Materials Science,
and MAPEX Center for Materials and Processes

University of Bremen
Faculty of Production Engineering
TAB-Building, Room 3.32
Am Fallturm 1
28359 Bremen, DE

http://www.hmi.uni-bremen.de/

> Il giorno 8 giu 2023, alle ore 11:08, Paolo Giannozzi <paolo.giannozzi at uniud.it> ha scritto:
> 
> I have heard that in 2D systems some acoustic sum rules may yield funny results for acoustic modes close to q=0. The latest 7.2 version of the code should contain an improved ASR. See https://gitlab.com/QEF/q-e/-/merge_requests/1978 <https://gitlab.com/QEF/q-e/-/merge_requests/1978>
> 
> Paolo
> 
> On 6/8/23 00:12, Juliana Maria Abreu Da Silva Morbec wrote:
>> 	
>> You don't often get email from j.morbec at keele.ac.uk <mailto:j.morbec at keele.ac.uk>. Learn why this is important <https://aka.ms/LearnAboutSenderIdentification <https://aka.ms/LearnAboutSenderIdentification>>
>> 	
>> Dear Lorenzo.
>> Thanks for your response.
>> I am attaching here the input files for scf and phonon calculations of bulk MoS2, as well as output files of dynmat.x using asr='simple' and asr='crystal'. I also noticed that asr='no' give similar results to asr='crystal'.
>> Regards,
>> Juliana
>> -----
>> *Dr Juliana Morbec*
>> Lecturer in Physics
>> Keele University, UK
>> ------------------------------------------------------------------------
>> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of Lorenzo Bastonero <lbastone at uni-bremen.de>
>> *Sent:* 06 June 2023 14:28
>> *To:* Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
>> *Subject:* Re: [QE-users] asr in dynmat.x
>> Dear Juliana,
>> In principle at Gamma the acoustic sum rules should only affect the 3 acoustic modes, setting them to 0, and leave the other modes close to their values ( ~< 1/0.1 cm-1).
>> If you are experiencing huge change in the wavenumber, it may probably be a sign of under converged calculations. Hard to say though w/o inputs/outputs.
>> HTH,
>> Lorenzo
>> ********************************
>> Lorenzo Bastonero
>> PhD Student
>> U Bremen Excellence Chair,
>> Bremen Center for Computational Materials Science,
>> and MAPEX Center for Materials and Processes
>> University of Bremen
>> Faculty of Production Engineering
>> TAB-Building, Room 3.32
>> Am Fallturm 1
>> 28359 Bremen, DE
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>>> Il giorno 6 giu 2023, alle ore 15:14, Juliana Maria Abreu Da Silva Morbec <j.morbec at keele.ac.uk <mailto:j.morbec at keele.ac.uk> <mailto:j.morbec at keele.ac.uk <mailto:j.morbec at keele.ac.uk>>> ha scritto:
>>> 
>>> Hello.
>>> 
>>> I have a question regarding the 'asr' feature in dynmat.x. I am computing Raman spectra of MoS2 bulk and I noticed that asr='simple' and asr='crystal' give different frequencies but similar amplitude for Raman. And asr='crystal' seems to be in better agreement with experiments. How to decide which one to use?
>>> 
>>> Thank you,
>>> 
>>> Juliana Morbec
>>> Lecturer in Physics
>>> Keele University, UK
>>> ----------
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>> Please consider the environment before printing this email.This email and its contents may be legally privileged and /or confidential.If it has come to you in error you should not copy or show it to anyone; nor should you take any action based on it, other than to reply to the sender to notify them of the error immediately and to then delete the email from your inbox and deleted items. Keele University staff and students are required to abide by the University's IT Policies when sending and receiving email. Keele University email is hosted by a cloud provider and may be stored outside of the UK.
>> _______________________________________________
>> The Quantum ESPRESSO community stands by the Ukrainian
>> people and expresses its concerns about the devastating
>> effects that the Russian military offensive has on their
>> country and on the free and peaceful scientific, cultural,
>> and economic cooperation amongst peoples
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> 
> -- 
> 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
> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
> country and on the free and peaceful scientific, cultural,
> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu <http://www.max-centre.eu/>)
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