CCL:G: GAUSSIAN: Displacement of normal modes in the electronic excited state

 Dear Shahnawaz,
Indeed, the displacement vector (along with the Duschinsky matrix) are used to evaluate the FC integrals, so the right way to proceed is to compute such parameters directly from their definition in terms of the normal mode matrices and structural displacements (see, e.g, http://link.aip.org/link/?JCP/41/3453/1 -Eq. 11).
Such analysis can be done with a variety of programs, as, for instance, FCclasses (http://www.pi.iccom.cnr.it/fcclasses), which can interface to a variaty of QM codes (see https://github.com/jcerezochem/fcc_tools). In Gaussian09, you can also get the shift vector as explained in the manual (http://www.gaussian.com/g_tech/g_ur/k_freq.htm). Take a look to the option PrtMat=/N/ from Freq=ReadFC (it seems that PrtMat=2 is what you want). 
 Javier
 El 11/07/16 a las 17:48, Shahnawaz Rather shahcmt2009()gmail.com escribió:
 
 Sent to CCL by: "Shahnawaz  Rather" [shahcmt2009(-)gmail.com]
 Hi Everyone,
   I am interested in finding the displacement of all the IR active modes in the
 excited state. For that I started with ground state optimization and frequency
 calculations followed by excited state optimization of the desired electronic
 state and the frequency calculation of the excited state. I am not sure how to
 proceed ahead in order to find the displacement of the IR modes in the excited
 state? I can probably perform a Franck-Condon analysis and read information from
 check point files to calculate the absorption spectrum and the corresponding
 Franck-Condon factors for the 1-0 and 0-0 transition of a particular normal
 mode, whose ratio will give me the displacement through Huang-Rhys factor and
 then repeat this for every other mode. But at the same time, I believe that the
 Franck-Condon analysis calculates Franck-Condon factors from the displacement of
 the normal modes in the excited state itself, so why not to locate those
 displacement values directly. My question is, if !
   whatever I wrote above is true, where can I exactly find these displacement
 values for the normal modes in the excited state???
Your immediate response will be highly appreciated. 
 Thanks
 Shahnawaz Rather
 shahcmt2009**gmail.com
 Princeton University, USA
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 Javier CEREZO BASTIDA
 PostDoc Researcher
 ICCOM-CNR, UOS di Pisa
 56124 PISA (ITALY)