[CP2K:6288] Convergence problem wrt cutoff

[Krack, Matthias]

 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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