1. Malgorzata Biczysko, Julien Bloino, Vincenzo Barone
SIMULATION OF HIGH RESOLUTION VIBRATIONAL AND ELECTRONIC SPECTRA WITH A MULTIFREQUENCY VIRTUAL SPECTROMETER
Malgorzata Biczysko, Julien Bloino, Vincenzo Barone
vis-à-vis

2. Goal: virtual spectrometer = vis-à-vis comparison
From theory to spectra
Direct comparison with experiment
Accuracy  interpretation
Easy-to-use procedure + analysis tools
1. V. Barone, A. Baiardi, M. Biczysko, J. Bloino, C. Cappelli, F. Lipparini, Phys. Chem. Chem. Phys. 14,
2. V. Barone Ed. ‘Computational strategies for spectroscopy’ Wiley 2012

3. Unified and general theoretical model
Focus on nuclear part
Beyond vertical transitions and harmonic approximation
General formulations easily extensible to other spectroscopies
From 1 vibrational level to transitions between 2 PES
Vibrational averaged properties [1-3]
+ resonance-free anharmonic ZPVE and thermodynamic properties
Vibrational spectroscopies [1-3]
General vibrational perturbative model for IR, Raman, VCD
Resonance-free treatment of frequencies and intensities
GVPT2, DVPT2, HDCPT2 [1-3]
Vibronic transitions [4-7]
Franck-Condon+Herzberg-Teller, Duschinsky mixing
Fully coherent time-independent (sum-over-states)[4-5] and time-dependent (path integral)[6] approaches for OPA, OPE, ECD, CPL
ab initio derived anharmonic corrections for excited [7] electronic states
General theoretical framework
Born-Oppenheimer approximation
Single excited electronic state at the time
Eckart conditions
JCP 122, (2005)
JCTC 8, 1015 (2012)
JCP 136, (2012)
JCTC 5, 540 (2009); 6, 1256 (2010)
JCP, 126, (2007)
JCP submitted
JCP 128, (2008)

4. Computational Strategy
Integrated QM approach
Accurate + feasible
Validation of low-cost yet reliable moldels
Eg. DFT/N07D (B3LYP, CAM-B3LYP)1,2
Hybrid QM/QM’ approaches3-5
Eg. CC/DFT, MRCI/DFT, B2PLYP/B3LYP
Higher level
Properties at ‘bottom of the well’
Harmonic frequencies
Vertical electronic transitions
Lower level
Anharmonic corrections
Excited states PES
Environmental effects
PCM: non equilibrium solvent effects including cavity fields6
integrated QM/FQ/PCM7 model for both time independent and time dependent approaches
DFTB/PCM and TD-DFTB/PCM8
General Liquid Optimized Boundary (GLOB) discrete/continuum model9
1. VB, JB, MB
PCCP, 12, 1092 (2010)
2. MB, P. Panek, G. Scalmani, JB, VB,
JCTC 6, 2115 (2010)
3. C. Puzzarini, MB, VB
JCTC 6, 828 (2010)
4. MB et al.
Theor. Chem. Acc. 113, 1201 (2012)
5. VB, MB, JB C. Puzzarini,
PCCP 15, (2013)
6. C.Cappelli, JB, F.Lipparini, VB
JPCL. 3, 1766 (2012)
7. F. Lipparini, F. Egidi, C. Cappelli, VB
JCTC 9, 1880 (2013)
8. VB, I. Carnimeo, G. Scalmani
JCTC 9, 2052 (2013)
9. G. Brancato., N. Rega, VB
JCP 128, (2008)

5. CC/DFT IR anharmonic spectra : pyrimidine
vs Experimental spectra
Vibrational freq in cm-1, Intensities in km/mol, GVPT2/DVPT2, DFT/SNSD
Mean Absolute Error (MAE), and largest negative (MIN) and positive (MAX) deviations with respect to experiment (Ar Matrix, S. Breda et al. J. Mol. Struct. 786, 193 (2006)
Computed
MB, J. Bloino, G. Brancato, I. Cacelli, C. Cappelli, A. Ferretti, A. Lami, S. Monti, A. Pedone, G. Prampolini, C. Puzzarini, F. santoto, F. Trani, G. Villani, Theor. Chem. Acc. 113, 1201 (2012)
CC = CCSD(T)/VTZ + QZ(MP2/VQZ-MP2/VTZ) + CV(MP2/CVTZ) + aug(MP2/aVTZ-MP2/VTZ)

6. IR anharmonic spectra in solution: pyrimidine
Solvent effects: non-equilibrium implicit (PCM) solvent1
Non-equilibrium approach simulates the slower reorganization of the solvent molecules with respect to the vibrations.
Computation: B3LYP/aug-N07D, Broadening: Lorentzian, HWHM=4cm-1
Experiment: 10% in CCl4 ( cm-1), 10% in CS2 ( cm-1)
C. Cappelli, F. Lipparini, J. Bloino, V. Barone, J. Chem. Phys, 135, , 2011
M. Biczysko et al. Theor. Chem. Acc., 131, 1201 (2012)

7. Vibrationally resolved electronic spectra of pyrimidine: S1S0
Computed [1] vs experimental [2] spectra:
FCHT|AH spectrum, Gaussian broadening with HWHM of 1 cm-1
TD-CAM-B3LYP/aug-N07D + anh CC/B3LYP + anh S0/S1
Assignment of vibronic bands
the most intense absorptions: in-plane ring deformations of A1symmetry
Reassignment: the band at about 3.98 eV (1000 cm-1 wrt 0-0) is related to the ’7 fundamental rather than to some overtone transition as proposed in [2].
Approximate models for excited state PES
1. M. B et al. Theor. Chem. Acc., 131, 1201 (2012)
2. S. F. Ferreira et al. PCCP. 12, 6717 (2010)
FCHT|AH and FC|VG

8. Pyrimidine: electronic spectrum in the 3.5-9.5 eV energy range
Computed [1] vs experimental [2] spectra:
FC|VG level, Gaussian broadening with HWHM of eV
Several (S1 -S12) excited electronic states
the hybrid CIPSI3/DFT (TD-CAM-B3LYP/aug-N07D) approach
1. MB et al. TCA., 131, 1201 (2012)
2. S. F. Ferreira et al. PCCP 12, 6717 (2010)
Verical Energies (eV)
3. CIPSI: R. Cimiraglia, M. Persico, J. Comput. Chem. 8 , 39 (1987)

9. Anharmonic IR and Raman spectra of unstable species: phenyl radical
Exp
CC/DFT IR of C6H5 and C6D5 [1]
CCSD(T)/aug-cc-pVTZ harmonic frequencies +IR intensities,
B3LYP/SNSD anharmonic contributions computed by the GVPT2/DVPT2 [2] model
Overall accuracy
Exceptional cases (e.g 23 of C6D5)
Less certain assignment
Reinvestigation?
with the help of fully anharmonic IR and/or Raman spectra
accounting for the species possibly present in the experimental mixture
including a few sets of isotopically substituted precursors
C6H5: |MAX|: 32 cm-1 MAE: cm for 24 normal modes
C6D5: |MAX|: 38 cm-1 MAE: 11 cm for 16 normal modes
[1] V. Barone, M. Biczysko, J. Bloino, F. Egidi, C. Puzzarini, J. Chem. Phys. In press
[2] J. Bloino, V. Barone, J. Chem. Phys (2012), V. Barone J. Chem. Phys. 122, (2005)

10. IR and Raman spectra of flexible molecules
Butane anti- and gauche- conformer abundances at 298 K
B3LYP/SNSD; Spectra GVPT2/DVPT2; G=SPT/HDCPT2, 64% anti-, 36 % gauche-
anti+gauche IR
Raman
Generalized VPT2/Deperturbed VPT2 JCP 136, (2012)
Simple Perturbation Theory, D. Truhlar JCP 94, 357 (1991), JCTC 8, 1015 (2012)
Hybrid Degeneracy Corrected PT2 JCTC 8, 1015 (2012)

11. IR and Raman of mixture: molecule and its complexes
Example: IR and Raman spectra of formic acid (+ its dimers)
Computation: B3LYP/SNSD, vacuum, Broadening: Lorentzian, HWHM=2cm-1
Experiment: A. Olbert-Majkut et al., Chem. Phys. Lett. 468, 176 (2009) , Ar matrix OD CD
Monomer IR
Raman -1
SUM
Exp. + =

12. Electronic spectra: beyond Franck-Condon approximation
S1←S0 absorption and electronic circular dichroism
(Z)-8-Methoxy-4-cyclooctenone (MCO)
ECD: several bands of opposite sign
OPA: the single broad band
S0: B3LYP/N07D; S1: TD-B3LYP/N07D, FWHM=500 cm-1
OPA
ECD spectrum:
Simple simulation based on vertical R [2]: more than three conformers necessary for qualitative reproduction of the experimental spectra.
Vibronic simulation + Herzberg-Teller effects: just one conformer reproduce the spectrum shape.
[1] VB et al, PCCP 14, (2012)
[2] T. Tanaka et al. Chirality 19, 415 (2007)

13. Integrated study on π-stacking interaction: the anisole dimer
Anisole moieties in dimer NOT equivalent: Two bands origins – difference in ZPVE energy.
simulated spectra as a sum of single contributions with isotopic substitution on ‘excited’(*) or ‘spectator’ monomer.
Electronic excitation localized (97%) on one of the monomers.
S0-M05-2X/6-31+G(d,p)
S1-TD-M05-2X/6-31+G(d.p)
FC|AH FWHM=2 cm-1 * + _
Electron density difference S1-S0
Energy [cm-1]
1. G. Pietraperzia, M. Pasquini, N. Schiccheri, G. Piani, M. Becucci, E. Castellucci, MB, JB, VB JPCA, 113, (2009)
2. N. Schiccheri, M. Pasquini, G. Piani, G. Pietraperzia, M. Becucci, M. B., J. Bloino, V. Barone, PCCP, 12, (2010)

14. Acknowledgements
V. Barone, C. Cappelli, I. Carnimeo, L. Carta, F. Egidi, D. Licari, M.Piccardo (SNS)
J. Bloino. F. Santoro, G. Prampolini, A. Ferretti, S. Monti (CNR)
Cacelli (UniPi)
C. Puzzarini (UniBo)
O. Crescenzi (UniNa)
M. Becuccci, G. Pietraperzia, M. Pasquini, G. Piani, F. Mazzoni, N. Schiccheri (LENS)
Goska