Get the geometry of the first isomer of Methylenpyren

Level of theory : DFTB SCC with BIO parameters

cat data/methylpyren_iso1.xyz >> deMon.inp

Optimize its structure in the cationic state :

 →  CHARGE +1

Use the optimized geometry as input for a new calculation

Perform a single point calculation and compute the elecronic spectrum (with LRESP subkeyword of DFTB)

Perform the same calculation for the second isomer of methylenpyren (again in cationic form) (OPTIMIZATION followed by TDDFTB calculation).

Compare the spectra for the two isomers.

How it compares with DFT results (see the TDDFT_results.dat file for results of TDDFT-B3LYP-6-31G(d,p)

Perform a Molecular Dynamics simulation (about 1000 steps).

Change intial energie (RANDOM keyword)

Compute and sum TDDFTB spectra periodically (FRESP keyword)

 →  DFTB SCC LRESP FRESP=10

Repeat for the two isomers and analyse the temperature evolution on the electronic absorption spectra of the two isomers. The spectrum is stored in spectrum_final.out that can be visualized with gnuplot.

gnuplot

p ’spectrum_final.out’ w l