[CP2K:10364] Re: Converging cutoff with QMMM

Dawid das add... at googlemail.com
Mon Jun 4 08:45:46 UTC 2018

Hi Matt,

Thank you for explaining. I made some checks and it seems that QM/MM
electrostatic embedding does
influence the convergence of SCF energy.

Actually I couldn't converge my SCF energy when it includes QM/MM
electrostatic energy.
If I do calculations in gas phase for my QM subsytem (with hydrogen atoms
capping) then I can
converge the energy for GAPW (&QS &METHOD) with reasonable CUTOFF and
(400 Ry and 60 Ry, respectively) but for GPW approach the convergence comes
at much higher

Best wishes,
Dawid Grabarek

2018-06-04 10:26 GMT+02:00 Matt W <mattwa... at gmail.com>:

> Hi Dawid,
> it shouldn't change anything, really. If you use the commensurate flag in
> a gas phase calculation you will get the same grids as you will get in the
> QMMM calculation and can do the standard tests.
> Matt
> On Friday, June 1, 2018 at 5:55:26 PM UTC+1, Dawid das wrote:
>> Dear Matt,
>> What if I use commensurate grids? Then according to the manual "*overrides
>> the progression factor and the cutoffs of the sub grids*".
>> So can I still use the described procedure to evaluate CUTOFF and
>> Excuse me if these questions are silly, but I'm completely new in this
>> part of
>> molecular modelling. Obviously, I am reading papers such as JCTC 2005, 1,
>> 1176
>> but still I do not get everything right away.
>> Dawid
>> W dniu piątek, 1 czerwca 2018 17:35:30 UTC+2 użytkownik Dawid das napisał:
>>> Dear CP2K Users,
>>> Can I use this tutorial
>>> https://www.cp2k.org/howto:converging_cutoff
>>> to choose cutoffs within &DFT &MGRID for QM/MM calculations with ECOUPL
>>> GAUSS?
>>> Best wishes,
>>> Dawid Grabarek
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