[Wien] System Error....Couldn't write to/.

Gavin Abo gabo13279 at gmail.com
Fri Jul 21 08:57:30 CEST 2023


That output file, case.outputd, as far as I know is not used an input to 
another calculation process. Thus, it seems safe to click the "initlapw 
without saving" button which would be another way to get around the 
"Couldn't write to /." error from "Save and initlapw" in this case.  
Although, if you are clicking the "initlapw without saving" or "Save and 
initlapw" button too quickly, you might have missed viewing the 
case.outputd to check if the condition gmax > gmin was meet.  Proceeding 
with a gmin value less then gmax could affect your results.

You didn't give the different file sizes of the case.outputd files for 
the BP, ZnSiP2 and other.  I suspect the file sizes are smaller than the 
case.outptud files produced for the C24H72N8In2Br14 and C16H20O7.

The TiC example in the usersguide [1] produces a case.outputd with a 
file size of about 21.8 kB.  That is a small unit cell and one of the 
calculation cases when the error is not observed.  The C16H20O7 has a 
relatively large unit cell [2] in comparison to that of TiC 
corresponding with the MB size case.outputd versus the kB one, respectively.

Whether you get the error "Couldn't write to /." or not with C16H20O7 
seems to also depend on the type of computer system(s) you are using 
(laptop, desktop, hpc? amount of RAM? SSD or HDD? how may CPU cores? 
using a virtual machine or not? Etc.).

For running calculation with WIEN2k, you have probably noticed how a 
single desktop computer is good for small unit cells but when moving to 
large structures such as slabs it can push researchers into using a hpc 
(e.g., the Roadrunner [3]).

At [4], you can probably see how there is quite a bit of difference in 
the computing ability and the computer resources between say a $1,700 
desktop and a $101,000,000 Roadrunner computer system.

[1] http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf
[2] https://doi.org/10.1007/s00894-022-05340-3
[3] https://en.wikipedia.org/wiki/Roadrunner_(supercomputer)
[4] 
https://insidehpc.com/2012/03/supercomputers-vs-your-computer-a-bang-for-the-buck-battle/ 



On 7/20/2023 10:23 PM, karina Khan wrote:
> Thank you for your response. I want to ask you that if I complete the 
> process by clicking continue initlapw without saving will it affect my 
> results as doing so I didn't find any error in scf convergence.
>
> One more thing this " System Error....Couldn't write to/." didn't 
> observe in other molecules like BP, ZnSiP2 and other.
>
> On Fri, 21 Jul, 2023, 8:14 AM Gavin Abo, <gabo13279 at gmail.com> wrote:
>
>     On an older, slower computer system, I was able to reproduce the
>     error displayed in w2web as:
>
>     *System Error*
>
>     Couldn't write to /.
>
>     _back to last page_
>
>     To produce the error, what I did in w2web was 1) I clicked the
>     "view case.outputd and cp case.in0_std case.in0" button, 2) paused
>     about 5 seconds, and 3) clicked the "Save and initlapw" button.
>
>     The file size of the case.outputd is 43.6 MB.  I suspect the error
>     results because my computer is slow in opening the case.outputd
>     file where I clicked on the save button before the file got opened up.
>
>     When I clicked "view case.klist" followed by clicking as fast as
>     possible "Save and initlapw", I do not encounter the same error. 
>     The file size of case.klist, however, is only 101 bytes.
>
>     I also 1) clicked the "view case.outputd and cp case.in0_std
>     case.in0" button, 2) paused about 1 minute, and 3) clicked the
>     "Save and initlapw" button.  When doing that, the error did not occur.
>
>     I put the 43.6 MB case.outputd on a new faster computer system
>     clicking the "Save and initlapw" button immediately after having
>     clicked the "view case.outputd and cp case.in0_std case.in0"
>     button and the error do not appear.
>
>     From that, it seems to be a computer system resource limitation
>     that is causing the error.
>
>     Kind Regards,
>
>     Gavin
>     WIEN2k user
>
>     On 7/14/2023 4:59 AM, karina Khan wrote:
>>     Ok I will keep this thing in my mind for future
>>     This command works well with different systems like Cs2AgInBr6,
>>     BP but not with system having molecular formula C24H72N8In2Br14
>>     and C16H20O7
>>
>>     On Thu, 13 Jul, 2023, 8:34 PM Peter Blaha,
>>     <peter.blaha at tuwien.ac.at> wrote:
>>
>>         I cannot reproduce this. It works perfectly fine with me.
>>
>>         Please try again in another case. Or use the recommended fast
>>         mode. This will set automatically good parameters in
>>         case.in0/1/2 and klist, and not the "stupid" defaults of the
>>         step by step initialization.
>>
>>         PS: You cannot send large images to the mailing list. There
>>         is a limit of 40 kB per message.
>>
>>
>>         Am 13.07.2023 um 11:48 schrieb karina Khan:
>>>         Dear Wien2k users,
>>>                                During initialisation, I stuck up in
>>>         the step *view case.outpd and cp case.in0_std case.in0,
>>>         *when I click on the step save and initlapw, I get a *System
>>>         Error couldn't write to/. * back to last page.
>>>         However this step is working for the other sample but not
>>>         for this new sample having 32 atoms.
>>>         Looking for your suggestions
>>>         *Thanks & Regards*
>>>         *Karina Khan*
>>>
>>>
>>>         _______________________________________________
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>>>         SEARCH the MAILING-LIST at:http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>>
>>         -- 
>>         -----------------------------------------------------------------------
>>         Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
>>         Phone: +43-158801165300
>>         Email:peter.blaha at tuwien.ac.at           
>>         WWW:http://www.imc.tuwien.ac.at       WIEN2k:http://www.wien2k.at
>>         -------------------------------------------------------------------------
>>
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