Dear Jibiao Li,
A late reply, but: It is not possible to "isolate" the molecule in the
calculation nor in the experiment, as any photon hitting the system might
cause an electronic excitation, either at the molecule or the surface, so
the intensity of the spectrum would be beyond the non-resonant regime.
The crude approximation is to calculate the vibrational modes and try to
correlate those with experiments - without the intensity (but maybe with
the selection rules from symmetry). Next, you might try to move the atoms
along the normal modes and see if you get something useful from the
variation/derivative of the dipole/polarisability. But, as said, also in
the experiment there could be any excitations, thus smearing the
intensities.
Greetings from Paris,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / ari.p.seitso...@iki.fi / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Tue, 9 Jan 2018, jibiaoli wrote:
Dear All,
I learned from the maillist that pure metallic systems do not have IR and Raman
active modes, thereby it's meaningless to calculated IR and Raman
spectra for those systems. However, I am very much interested in molecules
adsorbed on metal surfaces, is it possible to get IR and Raman spectra
for molecules/metal systems through QE calculations?
Best
Jibiao Li
Yangtze Normal University, China
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