1. GOAL: a quantitative interpretation of the vibrational spectra
The amount of information we can obtain from a vibrational spectrum
depends on our ability to translate spectroscopic observables
(frequency and intensity) in terms of molecular architecture
GOAL: a quantitative interpretation of the vibrational spectra
(IR and Raman) i.e. the assignment of the whole spectrum to
the respective normal modes of vibration:
INTERPRETATION STRATEGY
THEORETICAL APPROACH
NORMAL COORDINATE ANALYSIS (Wilson GF method):
Input: 1. Geometry (G matrix)
2. Energetics (Force constants, F matrix)
Secular equation:
Output: 1. Eigenvalues (frequencies)
2. Eigenvectors (nuclear displacements)
3. IR Intensities
COMPUTATIONAL METHODS:
1. MOLECULAR MECHANICS (to explore the potential energy surface)
2. DENSITY FUNCTIONAL THEORY, DFT (to refine geometry parameters
and to evaluate the energetics (Force Constants)

2. Polistirene sindiotattico forma a (zig-zag planare)

4. Risultati dell’analisi
vibrazionale

5. Polistirene sindiotattico forme g, d, e (elica s(2/1)2

7. Conformational Search (Molecular Mechanics)
force field MM+
Un polimero amorfo
Unsaturated polyester (propylene glycol / maleic anhydride)
Diethylfumarate (DEF)

8. DFT
 : Raman
 : IR
NCA