# CCL:G: Help with Geometry Opt for first singlet excited state
usingTDDFT

*From*: Mariusz Sterzel <m.sterzel(a)cyf-kr.edu.pl>
*Subject*: CCL:G: Help with Geometry Opt for first singlet excited
state usingTDDFT
*Date*: Thu, 9 Mar 2006 13:26:45 +0100 (CET)

Sent to CCL by: Mariusz Sterzel [m.sterzel^^^cyf-kr.edu.pl]
Hello,

`I disagree, it is possible to optimize excited states geometry with
``gaussian but it is computationaly very very expensive. I agree that
``TURBOMOLE is much better choice since it does have analytical
gradients.
``This also allows you to calculate harmonic frequencies.
` Anyway going back to gaussian, this question was asked several times.
The answer I got some time ago from
http://www.ccl.net/chemistry/resources/messages/2002/04/11.009-dir/
is:
1) build _GOOD_ z-matrix for your molecule
2) optimize ground state with opt(z-matrix)
3) calculate frequencies at optimized geometry
4) use following input for say 3rd excited state opimization
TD(NStates=5,Singlets,Root=3) Opt(ReadFC,Z-matrix,EnOnly)

`in addition to your usual gaussian settings. You can also use forces
from
``CIS calculation.
`

`Gradients are numerical so use as high symmetry as possible for
``optimization. And you cannot calculate frequencies so I'd rather use
``TURBOMOLE (which also have analytical gradients for excited states at
``CC level).
` Mariusz
--
Mariusz Sterzel
Email: m.sterzel/^at^\cyf-kr.edu.pl
On Thu, 9 Mar 2006, Jens Spanget-Larsen spanget=ruc.dk wrote:

Sent to CCL by: Jens Spanget-Larsen [spanget[A]ruc.dk]
Dear CY,
TD-DFT geometry-optimization of an excited singlet state is not possible
with Gaussian03. Turbomole has this facility.
Jens >--<
------------------------------------------------------
JENS SPANGET-LARSEN Office: +45 4674 2710
Department of Chemistry Fax: +45 4674 3011
Roskilde University (RUC) Mobile: +45 2320 6246
P.O.Box 260 E-Mail: spanget+*+ruc.dk
DK-4000 Roskilde, Denmark http://www.ruc.dk/~spanget
------------------------------------------------------
Changyong Qin changyong(-)wsu.edu wrote:

Sent to CCL by: "Changyong Qin" [changyong|-|wsu.edu]
Dear All,
Does anybody have experience in using TDDFT in Gaussian 03 to optimize the first
singlet excited state? If yes, could you please share the input file ? Thanks.
CY>