[CP2K-user] [CP2K:18436] Re: SG-CPMD - Thermalisation problem

[Marcella Iannuzzi]

Dear Simone 

It is all correct. The keyword TEMPERATURE within the thermal region is 
used for initialisation of the velocities

Kind regards
Marcella

On Friday, February 10, 2023 at 2:48:21 AM UTC+1 Simone Ritarossi wrote:

> 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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