[CP2K:8645] Comparison between CP2K and Quantum Espresso

[tfran... at gmail.com]

Dear Prof. Hutter,
first of all, thanks a lot for your kind reply.


Il giorno lunedì 6 febbraio 2017 16:04:41 UTC+1, jgh ha scritto:
>
> Hi 
>
> without additional information (e.g. output files or complete input) 
> I will have to do guessing. 
>
> There are two parts to this calculation 
> - time per SCF step 
> - number of SCF steps needed for convergence 
>
> SCF convergence: you start from an atomic guess (CP2K) and a random 
> wfn (QE). Although the convergence asked for is the same (1.e-7) 
> this means different things in the two codes (check change in energy 
> for the last step). For CP2K you can optimize the settings for the  

convergence, but as you do start from scratch only once the more 
> important part is what is the timing per step. 
> (You probably also don't need CHOLESKY OFF?, 
>  you use the most expensive PRECONDITIONER, 
>  DIIS might not be good to start with ...) 


Ok, i will check this part in detail in order to better tune the input to 
my and to get rid of the "most" expensive part as much as I can.

 

>
> Your settings are ok, but rather tight in many respect, e.g. large and 
> diffuse basis set, high cutoff. Non orthorhombic cell is also not 
> optimal for CP2K. 
>

Ok, I will decrease the settings parameters in order to allow a better 
flexibility in terms of the cutoff eat. 
Unfortunately all the systems I am dealing with are or monoclinic or 
triclinic. Now that I am aware of this pitfall, I will reset all the 
parameters in order to enhance the jobs as much as they can.
 

> So this is a very expensive calculation in CP2K standards. 
>
> regards 
>
> Juerg 
>
>
Thanks a lot again for clarifying me these crucial points!
Best Regards,

Tommaso 

> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Institut für Chemie C                FAX   : ++41 44 635 6838 
> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: -----To: cp2k <
> cp... at googlegroups.com <javascript:>> 
> From: tfra... at gmail.com <javascript:> 
> Sent by: cp... at googlegroups.com <javascript:> 
> Date: 02/05/2017 08:06PM 
> Subject: [CP2K:8645] Comparison between CP2K and Quantum Espresso 
>
> Dear all,I am currently testing my new machine, which is a cluster 2 
> Supermicro 2048U RT4 nodes with 4x2.6GHZ Intel Broadwell 10Core CPUs.The 
> point is that in order to check the scalability and the performances of the 
> machine with 40 processors, I run several single point calculations of the 
> same structure both with CP2K version 4.1 ssmp and Quantum Espresso 
> 5.1.1 It turns out that for the time spent by CP2K to converge a single 
> point calculation with 40 processors, for a system of 256 atoms, was of the 
> order of 13316.63 seconds (taken from the output in the TIMING BLOCK in the 
> end of the output file [TOTAL TIME AVERAGE); whereas for the QE, the same 
> calculation, with the same system ect. took just 1845.76 seconds. So, 
> because we strongly want to work with CP2K, also for running some dynamics 
> and exploit its scalability, may i ask you to kindly check if the input 
> file of the CP2K I used is properly set? I am more expert in QE rather than 
> CP2K, so I might have miss something essential. 
> For matter of comparison I attached the two input files used, one for the 
> CP2K and the other of the QE. 
> Thanks in advance for the kind help! 
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>                                         Best Regards,Tommaso  
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> [attachment "cp2k.inp" removed by Jürg Hutter/at/UZH] 
> [attachment "qe.inp" removed by Jürg Hutter/at/UZH] 
>
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