instability on scf during geoopt

[Matt W]

Hi Jun,

I do see the behaviour you describe.  What I tried to hint at above is
that you'll converge (to the same solution) if you use a restricted
wavefunction.  I've seen this for another system of my own.

I'm not sure if it is just the smaller number of degrees of freedom
that help the non UKS converge, whether the settings for the mixing
should be altered for UKS or whether there may be something else.
I'll try and cut down my system too.

Cheers,

Matt

On Mar 19, 6:40 pm, Jun <chen... at googlemail.com> wrote:
> Thanks for the reply, Matt.
> I am afraid that I cannot get the first scf converged for a smaller
> cell. Don't know if it is related to the lack of k-point sampling
> being inappropriate for a small system.
> I keep trying to find a smaller system having the same problem.
> Anyway, the present system is not that big, I am grateful if anyone
> being able to reproduce the problem can help.
>
> Cheers,
> Jun
>
> On Mar 19, 5:15 pm, Matt W <mattwa... at gmail.com> wrote:
>
> > Can the problem be made smaller?  Is it enough just to use UKS and a
> > small system to get convergence problems?
>
> > Matt
>
> > On Mar 19, 2:19 pm, Jun <chen... at googlemail.com> wrote:
>
> > > Hi all,
>
> > > I have been testing on some metallic system using diagonalization
> > > method. I used a set up found in a previous post with small changes.
> > > It works well for the first scf run; wavefunction got converged with a
> > > few tenth steps. But in the following geoopt, wavefunction cannot get
> > > converged. I played a bit with extrapolation method (PS and ASPC) and
> > > order, and it didn't help. Any suggestion and help are much
> > > appreciated. My input file (td.inp) is uploaded.
>
> > > Thanks.
> > > Jun