<div dir="ltr">A further observation: you specify PERIODIC NONE in the &CELL section, but there seems to be no &POISSON section with the same setting. Matthias On Tuesday, 24 March 2015 19:03:45 UTC+1, Valérie wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">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:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"> <div bgcolor="#FFFFFF" text="#000000"> 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 <div>On 24/03/15 17:40, Valérie wrote: </div> <blockquote type="cite"> <div dir="ltr">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: <a href="http://www.cp2k.org/howto:converging_cutoff" rel="nofollow" target="_blank" onmousedown="this.href='http://www.google.com/url?q\75http%3A%2F%2Fwww.cp2k.org%2Fhowto%3Aconverging_cutoff\46sa\75D\46sntz\0751\46usg\75AFQjCNFnuxmJU7f0gdukVHPM7DfJudfcAA';return true;" onclick="this.href='http://www.google.com/url?q\75http%3A%2F%2Fwww.cp2k.org%2Fhowto%3Aconverging_cutoff\46sa\75D\46sntz\0751\46usg\75AFQjCNFnuxmJU7f0gdukVHPM7DfJudfcAA';return true;">http://www.cp2k.org/howto:converging_cutoff</a> 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 </div></blockquote> </div> </div></blockquote></div></blockquote></div>