# CCL:G: TDDFT in gaussian

*From*: Jens Spanget-Larsen <spanget!A!ruc.dk>
*Subject*: CCL:G: TDDFT in gaussian
*Date*: Mon, 31 Jul 2006 10:59:29 +0200

Sent to CCL by: Jens Spanget-Larsen [spanget^^ruc.dk]
Dear Agalya Govindasamy,

`maybe you already solved your problem. But nevertheless, for a closed
``shell species, it is easy to calculate the percentage contributions
from
``the coefficients printed by a Gaussian TDDFT run. The coefficients
refer
``to micro-configurations (not spin adapted). If you want the percentage
``contribution from the pertinent singlet configuration, you must square
``the printed coefficient and multiply it by 2 x 100. For instance, the
``contribution from the 129 -> 138 excitation in the first of your
``examples amounts to
` 0.45069^2 x 2 x 100 = 40.62%.
In your second example, you get for the 130 -> 132 excitation
0.67417^2 x 2 x 100 = 90.90%.

`Please note that Gaussian by default prints only contributions larger
``than a certain treshold. There is an IOP input parameter that leads to
``printing also of smaller contributions, but I do not have it at hand.
` Good Luck!
Jens >--<
------------------------------------------------------
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Department of Chemistry Fax: +45 4674 3011
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------------------------------------------------------
Agalya Govindasamy agalya81{}gmail.com wrote:

Sent to CCL by: "Agalya Govindasamy" [agalya81-x-gmail.com]
Dear CCL users,
I would like to know about calculating the precentage contribution of excitation
coefficients given in the TDDFT output.
For example, the following excitation shows mixture of transitions with
different excitation coefficients.
Excited State 31: Singlet-A 3.6351 eV 341.07 nm f=0.0001
119 ->132 0.11466
124 ->138 0.16417
124 ->140 -0.16712
129 ->138 0.45069
129 ->140 -0.3978
129 ->141 -0.12337
130 ->136 -0.10225

`I have seen in some journals, that they have mentioned the
coefficients as percentage. Here since there are many transitions, could anyone
can please tell me how to calculate the percentage of the coefficients.
``
``This may be a stupid question.
``
``Does everyone divide the particular coefficient divided by the sum of
all the coefficients and then multiplied by 100 to get the percentage value?
``
` If that is correct, then how to get percentage value of the coefficient for
excitations like the following case
Excited State 1: Singlet-A 1.5328 eV 808.90 nm f=0.0287
130 ->132 0.67417

`can i mention it as 100%.
``
` Thankyou in adavnce