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[MANUEL PEREZ JIGATO <mpj@fyslab.hut.fi>]

hi,

regarding your question on tddft, i've been looking at
the tests and 55 seems to employ a total of 12 states, 5
occupied and 7 unoccupied.

Frequency representation linear response tddft computations
either in the Petersilka single-pole approximation or in the
full matrix method (Casida) seem to require a HUGE number of
unoccupied states for the sake of accurate excitation energies.

as far as i can gather from the literature, the number of unoccupied
states needed should at least something like "3 times" the number
of occupied states.
 
i hope that could help, however, i've never run tddft on abinit
myself


manolo




On Tue, 25 Feb 2003 luppi.eleonora@unimore.it wrote:

> Dear All,
>  I'm trying to make some calculations with TDDFT.
>  I'd like to have some information about TDDFT implementation in ABINIT. 
>  I have read that I can use: ixc 22=>  the Burke-Petersilka-Gross 
>  hybrid xc-kernel, for TDDFT tests.
>  Is it for tests only or for production too?
>  My problem is that I have performed some tests and I have obteined 
> incoherent results,
>  in particular wrong for ixc 20, 21,22, with respect to the case with ixc 7 
> or 1.
>  (as in test :Test_v3/t55.in). 
>  Another question is: have I to generate ad hoc pseudopotentials to use 
> this special xc-kernels 
>  or can I use simple LDA (or GGA-PBE) pseudopotentials.
> 
>  Any Help will be appreciated.
> 
>   Thank you 
> 
>    Best Regards Leo
> 

 
###########################################################################
 Manuel Perez Jigato
 Helsinki University of Technology
 Laboratory of Physics
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 FIN-02015 HUT
 Finland

 Tel: +358-(0)9-451 3107
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 E-mail: mpj@fyslab.hut.fi
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Quiere entrar alegre en Sevilla, donde un dia fue feliz, donde late el 
corazon del mundo (J. Eslava Galan)
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