The Born-Oppenheimer approximation is the most fundamental hypothesis in chemistry. On it rests our chemical intuition about molecular structure. In many situations, however, when the molecular system owns enough energy to explore unusual regions of the configuration space, the Born-Oppenheimer approximation may fail. In such regions, the adiabatic surface driving the time evolution of the system branches and the nuclear wavepacket will split among a manifold of states.
The occurrence of these nonadiabatic effects is not only common for a large number of problems, ranging from collision reactions to photochemistry, but it is the basis for key biochemical phenomena, such as light detection and the photostability of the genetic code.
The research in Barbatti's group is mainly focused on nonadiabatic processes that occur after molecular photoexcitation. These investigations are carried out by quantum-chemical calculations and excited-state dynamics simulations. Besides direct applications, the group also works on methodological developments, such as those included in the NEWTON-X program.
F. Plasser, M. Barbatti, A. J. A. Aquino, H. Lischka, Electronically excited states and photodynamics: a continuing challenge; Theor. Chem. Acc. 131, 1073 (2012). doi:10.1007/s00214-011-1073-y
M. Barbatti and M. A. C. Nascimento, Does the H5+ hydrogen cluster exist in dense interstellar clouds?; Int. J. Quantum Chem. doi: 10.1002/qua.24110 (2012).
Z. Lan, S. Nonell, and M. Barbatti, Theoretical Characterization of Absorption and Emission Spectra of an Asymmetric Porphycene; J. Phys. Chem. A 116, 3366 (2012). doi:10.1021/jp300888a
N. Kungwan, F. Plasser, A. J. A. Aquino, M. Barbatti, P. Wolschann, and Hans Lischka, The effect of Hydrogen Bonding on the Excited-State Proton Transfer in 2,(2'-hydroxyphenyl)benzothiazole: a TDDFT molecular dynamics study; Phys. Chem. Chem. Phys. 14, 9016 (2012). doi:10.1039/C2CP23905A
R. Crespo-Otero and M. Barbatti, Spectrum simulation and decomposition with nuclear ensemble: formal derivation and application to benzene, furan and 2-phenylfuran; Theor. Chem. Acc. 131, 1237 (2012).
M. Barbatti, Z. Lan, R. Crespo-Otero, J. J. Szymczak, H. Lischka, and W. Thiel, Critical appraisal of excited-state nonadiabatic dynamics simulations of 9H-adenine; J. Chem. Phys. doi:10.1063/1.4731649 (2012).
P. G. Szalay, A. J. A. Aquino, M. Barbatti, H. Lischka, Theoretical study of the excitation spectrum of azomethane; Chem. Phys. 380, 9 (2011).
J. J. Szymczak, M. Barbatti, and H. Lischka, Influence of the active space on CASSCF nonadiabatic dynamics simulations; Int. J. Quantum. Chem. 111, 3307 (2011).
M. Barbatti, J. J. Szymczak, A. J. A. Aquino, D. Nachtigallova, and H. Lischka, The decay mechanism of photo-excited guanine - a nonadiabatic dynamics study; J. Chem. Phys. 134, 014304 (2011).
R. Daengngern, N. Kungwan, P. Wolschann, A. J. A. Aquino, H. Lischka, M. Barbatti, Excited-State Intermolecular Proton Transfer Reactions of 7-Azaindole(MeOH)n (n=1-3) Clusters in the Gas Phase: On-the-fly Dynamics Simulation; J. Phys. Chem. A 115, 14129 (2011).
I. Borges Jr., M. Barbatti, A. J. A. Aquino, H. Lischka, Electronic spectra of nitroethylene; Int. J. Quantum. Chem. 112, 1225 (2011).
R. Crespo-Otero, M. Barbatti, H. Yu, N. L. Evans, S. Ullrich, The ultrafast dynamics of UV-excited imidazole; ChemPhysChem. 12, 3365 (2011).
M. Barbatti, A. J. A. Aquino, J. J. Szymczak, D. Nachtigallova, and H. Lischka, Photodynamical Simulations of Cytosine: Characterization of the Ultra Fast Bi-Exponential UV Deactivation; Phys. Chem. Chem. Phys. 13, 6145 (2011).
M. Barbatti, The role of tautomers in the UV absorption of urocanic acid; Phys. Chem. Chem. Phys. 13, 4686 (2011).
M. Barbatti, Nonadiabatic dynamics with trajectory surface hopping; WIREs: Comp. Mol. Sci. 1, 620 (2011).
R. Crespo-Otero and M. Barbatti, Cr(CO)6 photochemistry: Semi-classical study of UV absorption spectral intensities and dynamics of photodissociation; J. Chem. Phys. 134, 164305 (2011).
D. Nachtigallova, A. J. A. Aquino, J. J Szymczak, M. Barbatti, P. Hobza, and H. Lischka, Non-Adiabatic Dynamics of Uracil: Population Split Among Different Decay Mechanisms; J. Phys. Chem. A 115, 5247 (2011).
M. Pederzoli, J. Pittner, M. Barbatti, and H. Lischka, A non-adiabatic molecular dynamics study of the cis -trans isomerization of azobenzene excited to the S1 state; J. Phys. Chem. A 115, 11136 (2011).
M. Barbatti and S. Ullrich, Ionization potentials of adenine along the internal conversion pathways; Phys. Chem. Chem. Phys. 13, 15492 (2011).
The group interest focuses on ultrafast and nonadiabatic processes, including:
Systems of interest include:
As an example of application, with our collaborators in Vienna and in Prague, we have recently completed a comprehensive investigation of the ultrafast processes occurring in all five nucleobases composing DNA and RNA.
Our group has investigated the UV and visible spectrum of a number of molecules. The simulations are performed with a semiclassical method, which allows obtaining absorption cross section in absolute units and includes vibronic couplings.
In a recent investigation, we have used this methodology to show how the anomalous photophysics of urocanic acid, one of the main UV absorbers in our skin, can be explained by tautomeric effects.
The theoretical treatment of the time-dependent nonadiabatic phenomena for molecular systems is a formidable challenge in many levels, from the description of the excited states to the time propagation of their properties. Given that the full quantum mechanical solution of such problems for large molecules is out of question, several semiclassical approaches have been developed in the last half century to tackle the problem.
Our group dedicates to the development of tools for excited-state research, including nonadiabatic dynamics and spectrum simulations. In particular, we are among the main developers of the NEWTON-X program for surface hopping simulations.
Dr. Asturiol, David
Dr. Barbatti, Mario
Dr. Crespo Otero, Rachel
Teixeira Mancini, Daiana