[CPMD-list] some problems need your help

[Ari P Seitsonen]

Dear Shangyi,

   The easiest way to calculate the energy of the single atom is to use 
MULTIPLICITY of 4 (three unpaired electrons) and no FREE ENERGY 
FUNCTIONAL (and you can erase keyword 'STATES'). Please notice that you 
have a typo in 'TEMPERATURE ELCECTRON', however in this case it wouldn't 
matter because the default value is the same, but in case of molecular 
dynamics this would be interpreted as _ionic_ temperature. The cut-off 
energy of 60 Ry is probably much too high, maybe you used it just to find 
the problem in the convergence?

   Besides this, I also find the slow/missing convergence strange, as the 
initial guess of an atomic charge density with the atomic orbitals should 
be very close to the final solution.

   About partial DOS, I guess that you mean the projected density of 
states? You can check the keywords 'LDOS', and maybe 'POPULATION ANALYSIS' 
is interesting for you.

   About HOMO/LUMO, well for aluminium clusters they are probably not very 
important, but in general you get the eigenvalues directly printed out if 
using FREE ENERGY FUNCTIONAL, and if not you can perform a calculation 
with 'KOHN-SHAM ENERGIES'. For the wave functions, you can use either 
'RHOOUT BANDS' + cpmd2cube or the 'PROPERTIES' and 'CUBEFILE'.

   Hopefully this helps at least a bit.

      Greetings from San Sebastian,

         apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari P Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   CNRS & IMPMC, Université Pierre et Marie Curie
       4 place Jussieu, case 115 / F-75252 Paris
   Tel: +33-1-4427 7542, Fax: +33-1-4427 3785, GSM: +33-6-6736 3820

On Thu, 1 Dec 2005, Shangyi Ma wrote:

> Dear cpmd-user:
>   I have some problems need your help:
>   The first, I want to compute the energy of single Al atom, but it 's difficult converge through hundreds of steps or even two thousand! The following is my input-file, could you help me solve the problem:
> *************************************************
> &CPMD
>  OPTIMIZE WAVEFUNCTION
>  RESTART WAVEFUNCTION COORDINATES
>  CONVERGENCE ORBITALS
>  1.0D-5
>  FREE ENERGY FUNCTIONAL
>  LANCZOS DIAGONALISATION
>  LANCZOS PARAMETAERS N=5
>  50  6  20  1.0D-9
>  0.05  1.0D-10
>  0.01  1.0D-12
>  0.0025  1.0D-14
>  0.001  1.0D-16
>  LSD
>  ANDERSON MIXING
>  0.2
>  BROYDEN MIXING
>  BROYMIX=0.15
>  TEMPERATURE ELCECTRON
>  1000
>  CENTER MOLECULE ON
>  MIRROR
> &END
>
> &SYSTEM
>  SYMMETRY
>  0
>  MULTIPLICITY
>  2  #(for al atom, the 2S+1=2 ? or 4?)
>  POISSON SOLVER TUCKERMAN
>  ANGSTROM
>  CELL
>  12.0  1.0  1.0  0.0  0.0  0.0
>  STATES
>  10
>  CUTOFF
>  60
> &END
>
> &ATOMS
> *Al_SGS_LDA.psp KLEINMAN-BYLANDER
> LMAX=D
> 1
> 6.0  6.0  6.0
> &END
> **********************************************************
>
> Secondly, how can I get the Partial_DOS information of the system(for 
> example, the al cluster) that i compute? Could someone teach me details?
>
> Thirdly, how can I get the information of HOMO and LUMO about the system 
> that I compute?  More details is better!
>
> Any comments and help is appreciated!
> Thanks in advance!
> Best wishes!
>
> shyma