[CP2K:6288] Convergence problem wrt cutoff

[Valérie]

Dear Matthias, 

Thanks for the advice, I tried EPS_DEFAULT 1.0E-14 and turn off the 
smearing but it didn't help:

# Grid cutoff vs total energy
# REL_CUTOFF = 100
# Cutoff (Ry) | Total Energy (Ha) | NG on grid 1 | NG on grid 2 | NG on 
grid 3 | NG on grid 4
     50.00   -68.6591151507   51528     490       0       0
    100.00   -71.4960225951   49423    2499      96       0
    150.00   -71.3943595587   46649    4879     490       0
    200.00   -71.4042101807   45019    6209     790       0
    250.00   -71.4043240457   42959    7117    1846      96
    300.00   -71.4043467391   41354    8069    2499      96
    350.00   -71.4042672401   38632   10347    2847     192
    400.00   -71.4043262818   37146   10913    3671     288
    450.00   -71.4043453432   35187   11462    4879     490
    500.00   -71.4043447554   34568   11773    5187     490
    550.00   -71.4043353326   33159   11988    6081     790
    600.00   -71.4043429773   32597   12422    6209     790



On Tuesday, March 24, 2015 at 12:51:04 PM UTC-4, Matthias Krack wrote:
>
>  Dear Valerie, 
>
> you may try a smaller EPS_DEFAULT value like 1.0E-12 or even 1.0E-14. You 
> may also switch off the smearing, if your systems shows a decent band gap. 
> I would guess a cutoff of about 400 Ry should be sufficiently accurate.
>
> Matthias
>
> On 24/03/15 17:40, Valérie wrote:
>  
> Hi all, 
>
> I would like to run a geometry optimization of a single molecule with 
> Quickstep but got stuck at the first step; i.e. get meaningful values of 
> cutoff and relative cutoffs. 
> I followed this tutorial: http://www.cp2k.org/howto:converging_cutoff but 
> the total energy does not converge to great accuracy with my system:
>
> # Grid cutoff vs total energy
> # REL_CUTOFF = 100
> # Cutoff (Ry) | Total Energy (Ha) | NG on grid 1 | NG on grid 2 | NG on 
> grid 3 | NG on grid 4
>      50.00   -68.6591152269   51340     490       0       0
>     100.00   -71.4960226714   49235    2499      96       0
>     150.00   -71.3943596348   46461    4879     490       0
>     200.00   -71.4042102566   44831    6209     790       0
>     250.00   -71.4043241216   42771    7117    1846      96
>     300.00   -71.4043468150   41166    8069    2499      96
>     350.00   -71.4042673160   38450   10341    2847     192
>     400.00   -71.4043263577   36970   10901    3671     288
>     450.00   -71.4043454189   35016   11445    4879     490
>     500.00   -71.4043448309   34404   11749    5187     490
>     550.00   -71.4043354081   33007   11952    6081     790
>     600.00   -71.4043430530   32450   12381    6209     790
>
> I was wondering if there was something I could try to fix this or should I 
> carry on with Cutoff = 400?
>
> Many thanks
> Valerie
>
>  
>
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