[CP2K-user] [CP2K:17696] Re: SGCPMD: problem with equilibration?

Alexandra Dávila a.celinda.dl at gmail.com
Thu Sep 15 18:11:00 UTC 2022

Dear Onofrio!
you are right! It is too tight. I will try out what you recommende me!
Thanks a lot,

El jueves, 15 de septiembre de 2022 a las 12:53:45 UTC+2, 
onofr... at gmail.com escribió:

> Dear Alexandra,
> have you done an equilibration step before starting the SGCPMD run?
> As I can see from your plots it seems that it is not equilibrated yet. I 
> suggest you to make a BOMD run first for better equilibration, then 
> switching to sgcpmd, as follows:
> 1. BOMD as NVE ensemble + TEMP_TOL 100
> 2. switch to SGCPMD using RESTART.wfn of the previous equilibration step 
> as a wfn guess
> It works for me.
> Hope it helps
> Regards
> Onofrio
> Il giorno giovedì 15 settembre 2022 alle 12:04:35 UTC+2 
> a.celi... at gmail.com ha scritto:
>> Dear Cp2k users,
>> I have carried on a second-generation Car-Parrinello (SGCP) MD simulation 
>> for Pt(111)/water interface. Unit cell contains Pt: 6x6x4 (2 frozen 
>> layers), water: 134 molecules.
>> I have performed a similar workflow as Onofrio ("SGCPMD: number of steps 
>> per SCF run increase suddenly after initial 400 MD steps"). But I have 
>> used the NOISY_GAMMA as in the publication *"First-Principles 
>> Simulations of an Aqueous CO/Pt(111) Interface" 
>> doi:10.1021/acs.jpcc.8b05933, *Pt: 5E-05 1/fs and for water 2.2E-04 
>> 1/fs. Temperature is set to 330K. 
>> Unfortunately, in my case along the SGMD the temperature of Pt region 
>> drops to roughly 180 K, the temperature of the hole system is about 328K. I 
>> expected that the temperature of Pt region would be closer to the water 
>> after a equilibration time of 4ps. Does this mean that probably my system 
>> is not well-equilibrated? Is this going to affect the dynamics and energy 
>> of the system? (PS: the density profile seems ok, double peak on oxygen, 
>> well-known for Pt(111))
>> Many thanks in advance!
>> Alexandra
>> PS: I also observed the increase of the SCF steps after a restart!
>> TOP: red dashed line: average temperature of system
>> BOTTOM: temperature for each region
>> [image: SGMD_00MD_Temp.png][image: SGMD_00MD_TempLAN.png]

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