Terahertz spectroscopy

[yeilkim23]

Hey TM users!
Can anybody do analyze terahertz spectroscopy with TM?
I'm trying to, but I can't fine how to.
If anybody know the method page, answer me please!

[Arnim]

What exactly do you want to analyse? Rotational transitions or something else?

[yeilkim23]

#Arnim ! Thanks Just want to calculate vibrational modes! Is aoforce enough?

[Arnim]

Yes, first you have to optimise the structure and then run the vibrational analysis with aoforce or NumForce (depending
on the method you are using).

Cheers,
Arnim

[christof.haettig]

With aoforce you get the harmonic frequencies. They are usually kind of ok for intramolecular stretch and bend modes that appear in the
infrared region.

In THz spectroscopy your are typically interested in intermolecular modes, typically large amplitude motions, e.g. in the solvent shells.
For these modes the harmonic approximation doesn't work well.
A more appropriate approach for this regime is to compute the spectrum with a MD appraoch via the dipole autocorrelation function.