[CP2K:6941] Optimizing Nickel Cluster

[S Ling]

Hi Natalie,

I can see that you are dealing with metallic systems, and in both cases,
you are using the OT method for SCF convergence, which is not
recommended. For metallic systems, normally we use direct diagonalization
with Fermi-Dirac smearing. You may try to replace the &SCF section of your
input with the following section and see whether it works.

SL

========
  &SCF
     SCF_GUESS  ATOMIC
     EPS_SCF 1.0E-6
     MAX_SCF 500
     ADDED_MOS  200
     CHOLESKY INVERSE
     &SMEAR  ON
         METHOD FERMI_DIRAC
         ELECTRONIC_TEMPERATURE [K] 300
     &END SMEAR
     &DIAGONALIZATION
          ALGORITHM STANDARD
     &END DIAGONALIZATION
     &MIXING
          METHOD BROYDEN_MIXING
          ALPHA   0.1
          BETA    1.5
          NBROYDEN  8
     &END MIXING
  &END SCF



On 1 September 2015 at 18:14, Natalie Austin <natalie... at gmail.com>
wrote:

> Hello,
>
> I'm fairly new to cp2k. I've been attempting to study a Nickel (and
> copper) cluster on a ZnO support.
> So far using I've been able to converge the Copper cluster (~3 hrs) and
> the Cu on the ZnO support (~20hrs) using the input files below. However,
> I'm having an issue with the Nickel cluster.
> Initially I used the same input as with the copper cluster except I
> changed the basis, pseudopotentials.
> I've also I tried increasing the i) cutoff ,  ii) adding spin polarization
> with UKS  and iii) UKS and changing the multiplicity.
> However, the calculation runs for over 24 hours in each case and only
> performs 0-2 optimization steps. I just want to know if this is normal for
> a nickel system? and if there is anything else I could try to obtain
> convergence.
>
> Thanks,
>
> Natalie
>
>
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