[CP2K-user] [CP2K:18430] Re: SG-CPMD - Thermalisation problem

[Simone Ritarossi]

Dear Marcella,
Thanks for your reply. I want to ask you for some clarification on the 
input part to be added:

1) If I set DO_LANGEVIN_DEFAULT F and DO_LANGEVIN F I am associating my 
thermal region with an NVE molecular dynamics, right? I just want to 
"force" the titanium atoms to thermalise at 600 K, respecting a LANGEVIN. I 
must therefore choose .TRUE., right?

2) If I exclude NOISY_GAMMA_REGION, I am associating the thermal region 
with the NOISY_GAMMA_REGION chosen on the total system, right?

3) TEMP_TOL helps me with thermalisation, however doesn't this create 
'non-physical' molecular dynamics, i.e. molecular dynamics from which I 
cannot extract dynamic properties such as the diffusion coefficient?  

4) About LIST: I follow the implicit numbering of the atoms in the input 
file, right?

Many thanks in advance,
Simone

&THERMAL_REGION
       DO_LANGEVIN_DEFAULT  T
       &DEFINE_REGION
             DO_LANGEVIN T
             LIST  n1..n2
             TEMPERATURE     600
             #NOISY_GAMMA_REGION     2.1999999999999998E-04
             #TEMP_TOL 50
       &END DEFINE_REGION
 &END THERMAL_REGION
Il giorno mercoledì 8 febbraio 2023 alle 11:59:56 UTC+1 Marcella Iannuzzi 
ha scritto:

> Dear Simone, 
>
> You may define the thermal regions and set tuned  noisy gamma for each 
> region independently.
> CP2K_INPUT <https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT.html> / 
> MOTION <https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT/MOTION.html>
>  / MD 
> <https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT/MOTION/MD.html> / 
> THERMAL_REGION 
> <https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT/MOTION/MD/THERMAL_REGION.html>
>  / DEFINE_REGION 
> <https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT/MOTION/MD/THERMAL_REGION/DEFINE_REGION.html>
>
> Regards
> marcella
>
> On Monday, February 6, 2023 at 5:25:48 PM UTC+1 sim.ri... at gmail.com wrote:
>
>> Dear cp2k-users,
>>
>> I have thermalisation problems with my heterostructure, consisting of a 
>> GST + TiTe2 (633 atoms), where I consider van der Waals interactions (with 
>> DFT-D3). Initially I have a relaxed structure (CELL_OPT), which I want to 
>> thermalise at 600K. I am using the SGCPMD (&LANGEVIN). The problem is that 
>> the titanium atoms do not thermalise at 600K, but at a lower temperature, 
>> whereas the other atoms do so acceptably. I have also tried thermalising 
>> initially with an NVT and then using SGCPMD, but the problem persists. 
>> I cannot use TEMP_TOL so as not to affect dynamic properties such as 
>> diffusion etc etc.
>>
>> This also happens at 1300K (melting of GST). 
>>
>> In general, I have tried different gamma values. 
>>
>> I attached the input file.
>>
>> Many thanks in advance,
>> Simone
>>
>>

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