[CPMD-list] 143 steps too long?

[Juerg Hutter]

Hi
> I am doing  single point calculation for density minimization on BH4,
> cation.   Everything worked fined, but took 143 steps to complete.  Is this
> too long?  Incorrect?  I first used ODIIS and it took more than 1000 steps
> for wavefunction optimization.  When I used PCG Minimizer, that is when I
> got it down to 143 steps.  This was all done using the Vanderbelt
> psuedopotential.  The manual says that steps larger than 100 is to be
> considered slow. Does slow mean inaccurate in this case?  Any suggestions
> would be greatly appreciated.  Below is my input file:

For systems with a non-standard electronic structure it might take 143
steps to converge. If it converges it will not be inaccurate.
Systems like this are best treated using different approaches,
like starting out with PCG and switching later to ODIIS.
Usually we only need on wavefunction optimization from an initial
guess. Later on (in geometry optimization or BOMD) you can start
from much better guesses from previous calculations. They usually
converge much quicker.

BTW you are using Martins-Trouiller pseudos, not Vanderbilt.

regards

Juerg Hutter


>
>
> Matt  Wagner
> Cleveland State University
> Chemistry Dept.
> mattwagner at hotmail.com
>
> &CPMD
> WAVEFUNCTION OPTIMIZATION
> PCG MINIMIZE
> TIMESTEP
> 20
> &END
>
> &DFT
> FUNCTIONAL PBE
> &END
>
> &SYSTEM
> SYMMETRY
> 0
> CHARGE
> 1.0
> CELL
>   40.0000000    1.0000000    1.0000000    0.0  0.0  0.0
> CUTOFF
> 80
> &END
>
> &ATOMS
> *H_MT_PBE.psp  KLEINMAN-BYLANDER
>   LMAX=S
> 15
>   10.2206634   20.0283459   17.1559610
>   10.1261771   16.8725020   17.1559610
>   14.6615216   19.6881951   13.7922472
>   21.9369701   21.3700520   18.4409753
>   22.6928608   16.6268375   21.2566684
>   20.3118049   21.1999766   23.9211833
>   20.8220312   18.1008245   24.9794303
>   16.7780157   17.9118518   24.0912587
>   25.9053965   19.3480442   19.8960650
>   26.1510610   23.3731625   21.3511547
>   24.6959713   19.6692978   25.4707593
>   27.9651988   16.6646321   25.4518620
>   29.4958776   20.3307022   26.2077528
>   29.8738229   20.1228322   23.0141144
>   28.0029933   22.7684499   24.5636904
> *O_MT_PBE.psp  KLEINMAN-BYLANDER
>   LMAX=P
> 3
>   18.9889961   20.7653394   14.0568090
>   24.4881013   22.5983745   21.3133602
>   26.7179791   16.7024266   24.1101560
> *C_MT_PBE.psp  KLEINMAN-BYLANDER
>   LMAX=P
> 9
>   13.7166581   18.3464890   17.3071392
>   17.8929545   19.7826814   15.8709468
>   18.8189207   18.9512016   18.2331054
>   17.0614747   18.5165644   20.1039350
>   22.2393264   18.6299480   21.2377711
>   20.3307022   19.2157633   23.3353679
>   24.7904576   19.9527568   21.5212301
>   26.0943692   19.2913524   24.0156696
>   28.5321169   20.7842367   24.4314095
> *N_MT_PBE.psp  KLEINMAN-BYLANDER
>   LMAX=P
> 5
>   14.5292407   17.9874409   19.6315033
>   11.1277323   18.4220781   16.8158102
>   15.3229260   19.2157633   15.5307959
>   21.3322575   19.5748115   18.8000234
>   17.8929545   18.2142081   22.5416827
> &END
>
>
> _______________________________________________
> CPMD-list mailing list
> CPMD-list at cpmd.org
> http://cpmd.org/mailman/listinfo/cpmd-list
>