[CPMD-list] TDDFT force calculation not compatible with NLCC pseudopotential?

[Xiulin Ruan]

Dear Axel and Professor Hutter,

Thanks for your replies. Here I wanna add a little more information to make
our problem clearer. This problem arose when we was trying to do the excited
state geometry optimization. However, the TDDFT single point energy
calculations with the Ti_MT_LDA_NLCC pseudopotential worked pretty well, and
the calculated vertical excitation energies were good. This looks a little
surprising to us since geometry optimization is like a series of iterated
single point energy calculations. Hope you can help on this problem.

Thanks,

Xiulin


> -----Original Message-----
> From: cpmd-list-bounces at cpmd.org [mailto:cpmd-list-bounces at cpmd.org] On
> Behalf Of Juerg Hutter
> Sent: Tuesday, June 26, 2007 6:38 AM
> To: Hua Bao
> Cc: cpmd-list at cpmd.org
> Subject: Re: [CPMD-list] TDDFT force calculation not compatible with NLCC
> pseudopotential?
> 
> Hi
> 
> one of the problems of TDDFT geometry optimization is
> that you might get into areas where the geometry is far
> of the optimal ground state geometry. In those cases
> (restricted) Kohn-Sham calculations for the ground state
> are difficult and might result in unreasonable
> electronic structures.
> 
> I would check the ground state result, especially
> HOMO and LUMO energy for your last geometry.
> 
> regards
> 
> Juerg Hutter
> 
> ----------------------------------------------------------
> Juerg Hutter                   Phone : ++41 44 635 4491
> Physical Chemistry Institute   FAX   : ++41 44 635 6838
> University of Zurich           E-mail: hutter at pci.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
> ----------------------------------------------------------
> 
> 
> On Mon, 25 Jun 2007, Hua Bao wrote:
> 
> > Dear All,
> >
> > I am calculating Ti[H2O]6 cluster with TDDFT. The spectra result is
> pretty
> > good. However, TDDFT MD result is not reasonable. It has following
> warning
> > messages while calculating the TDDFT forces (also see my last post),
> >
> > CALCULATION OF TDDFT FORCES
> >
> > CPU TIME FOR INITIALIZATION OF LINEAR RESPONSE:     0.17 SECONDS
> > WARNING! First order density integral (R space)   1.40622137E-06
> > WARNING! First order density integral (R space)   3.17749222E-04
> >   NFI      GEMAX     CNORM         ETOT(2)        DETOT     TCPU
> >     1***********547.690471****************    0.000       37.130
> > WARNING! First order density integral (R space)   1.05641421E-03
> >
> > And the force is unreasonable (10^3 order). I am using Ti_MT_LDA_NLCC
> > pseudopotential and LDA functional. If I don't specify the
> pseudopotential
> > option of NLCC, then it will run normally. However, the electron spectra
> > result is not good. Is there any incompatible between NLCC and TDDFT
> force
> > calculation?
> >
> > If it is the case, can anyone give me some suggestions on choosing a
> proper
> > pseudopotential of Titanium? There is only NLCC pseudopotential for Ti
> in
> > CPMD package.
> >
> > Thanks,
> > Hua Bao
> >
> > Graduate Student
> > School of Mechanical Engineering
> > Purdue University
> > Office Tel: (765) 494-6944
> >
> >
> _______________________________________________
> CPMD-list mailing list
> CPMD-list at cpmd.org
> http://cpmd.org/mailman/listinfo/cpmd-list