vibrational mode intensities?

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dkersh02 · #1 Post by **dkersh02** » Thu Jun 12, 2008 3:21 am

Hi all,

Is it possible to approximate vibrational mode intensities using VASP for small molecules adsorbed on a metal surface? If so, how, i.e. where can I find relevant instructions?

Thanks

dkersh02 · #2 Post by **dkersh02** » Thu Jun 12, 2008 3:55 am

I guess another related (maybe more relevant) question is how do I calculate the dynamic dipole for each vibration mode.

#3 Post by **admin** » Thu Jun 12, 2008 2:15 pm

for IR active modes the intensities can be calculated from the oscillator strength of the corresponding mode; see eg.P.Giannozzi and S. Baroni, J.Chem.Phys. 100 (11), 8537 (1994). the effective charge tensors which enter the oszillator strength can be calculated by vasp (see the chapter on Berry phases in the online manual)

dkersh02 · #4 Post by **dkersh02** » Thu Jun 12, 2008 8:40 pm

perhaps I'm thinking of this too physically...the online manual states that the calculation of the Berry phase is for "the electronic polarization of an insulating groundstate system." I'm confused by the inclusion of "insulating" in the statement. Is this calculation only accurate for an insulator? Or since I'm not really interested in the vibration mode intensities of metal vibrations, only the adsorbates, perhaps it doesn't matter that I'm working with a metal substrate?