[QE-users] relax calculation on MD snapshots

[Giuseppe Mattioli]

Dear Chirantan
I see a solvated SO4 *neutral* species in your input, and it will  
never converge if you don't add the two missing electrons to obtain  
the proper stable solvated SO4(2-) anion. You should either add again  
the Mg species (this should lead by aufbau principle to the  
localization of 2 electrons on SO4(2-), letting back Mg(2+)) or impose  
a -2 total charge to the supercell, if this is compatible with your  
purposes.
HTH
Giuseppe

Quoting Chirantan Pramanik <chirantan.pramanik at weizmann.ac.il>:

> The input and output files are attached. I need a physical  
> explanation of why the atomic coordinates do not converge from an MD  
> simulation snapshot. The output shows the accuracy varies  
> periodically but never reaches the target accuracy. This one is with  
> cg diagonalization which is still running.
>
> Regards,
> Chirantan
> ________________________________
> From: users <users-bounces at lists.quantum-espresso.org> on behalf of  
> Giuseppe Mattioli <giuseppe.mattioli at ism.cnr.it>
> Sent: Sunday, February 23, 2025 4:57 PM
> To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
> Subject: Re: [QE-users] relax calculation on MD snapshots
>
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>
> Dear Chirantan
> As detailed in thousands of previous posts, it is totally useless to
> say "it does not converge" without providing all the details (input,
> output, QE version, pseudopotentials,...)
> HTH
> Giuseppe
>
> Quoting Chirantan Pramanik <chirantan.pramanik at weizmann.ac.il>:
>
>> Hello,
>>
>> I need to calculate phonon for some structures of Mg in water
>> obtained from MD simulations. I ran AIMD at 300K and performed 16000
>> steps with 1 fs time step. Then, I collected equidistant snapshots
>> from the temperature-stabilized region to compute phonon. However,
>> according to a few previous studies, they optimized all atomic
>> coordinates of the MD snapshots to get the reliable phonon required
>> for isotopic study. When I try to optimize, the structures never
>> converge. I tried using more steps and lower thresholds. But does
>> not work. Please help to solve this. Also, as the Mg ion resides in
>> the same water cage at this time, should most of the snapshots give
>> the same optimized structure?
>>
>> Regards,
>> Chirantan
>>
>>
>>
>>
>> Chirantan Pramanik
>> Postdoctoral Researcher
>> Dept. of Earth and Planetary Sciences
>> Weizmann Institute of Science
>> Rehovot, Israel
>
>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
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GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
Via Salaria Km 29,300 - C.P. 10
I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
Tel + 39 06 90672342 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>