Papers by Maurizio Persico
The journal of physical chemistry letters, Jan 15, 2016
While azobenzenes readily photoswitch in solution, their photoisomerization in densely packed sel... more While azobenzenes readily photoswitch in solution, their photoisomerization in densely packed self-assembled monolayers (SAMs) can be suppressed. Reasons for this can be steric hindrance and/or electronic quenching, e.g., by exciton coupling. We address these possibilities by means of nonadiabatic molecular dynamics with trajectory surface hopping calculations, investigating the trans → cis isomerization of azobenzene after excitation into the ππ* absorption band. We consider a free monomer, an isolated dimer and a dimer embedded in a SAM-like environment of additional azobenzene molecules, imitating in this way the gradual transition from an unconstrained over an electronically coupled to an electronically coupled and sterically hindered, molecular switch. Our simulations reveal that in comparison to the single molecule the quantum yield of the trans → cis photoisomerization is similar for the isolated dimer, but greatly reduced in the sterically constrained situation. Other implic...
Photodissociation dynamics of chlorine peroxide adsorbed on ice
Chlorine peroxide plays an important role in the chlorine-ozone chemistry in the antarctic strato... more Chlorine peroxide plays an important role in the chlorine-ozone chemistry in the antarctic stratosphere. Adsorption by ice crystals may alter its photochemistry in different ways. We have simulated the photodissociation of a ClOOCl molecule adsorbed on ice by means of a semiclassical representation of the excited state dynamics. Electronic energies and wave functions of ClOOCl are computed by an ad hoc reparametrized semiempirical method, and the interaction with ice is taken into account by a QM/MM strategy. The reaction mechanism is similar to what was previously found for the isolated molecule: sequential or almost simultaneous breaking of both Cl-O bonds leads to the 2Cl + O2 reaction products in most cases. The Cl atoms remain temporarily adsorbed on the ice surface, whereas O2 is ejected. The main effect for the overall chlorine chemistry is probably an increase of the photodissociation rates at long wavelengths, due to the change of adsorption cross sections induced by the interaction with ice.
The Journal of Chemical Physics, 1996
A hybrid quantum mechanical force field molecular dynamics simulation of liquid methanol: Vibrati... more A hybrid quantum mechanical force field molecular dynamics simulation of liquid methanol: Vibrational frequency shifts as a probe of the quantum mechanical/molecular mechanical coupling Quantum mechanics on multiply connected manifolds with applications to anyons in one and two dimensions AIP Conf.
Stochastic model for photoinduced anisotropy.
We present a stochastic model for the kinetics of photoinduced anisotropy in a sample of molecula... more We present a stochastic model for the kinetics of photoinduced anisotropy in a sample of molecular chromophores that may undergo photoisomerization. It is assumed that the chromo-phores do not interact among them, but are embedded in a medium that slows down the rotational diffusion. The model makes use of data about the photoinduced reorientation of the single chromophore, its photoisomerization and its rotational diffusion, that are made available by molecular dynamics simulations. For the first time such molecular scale processes are computationally connected to the development of anisotropy in a large sample and on a long time scale. A test on azobenzene shows the potentiality of the method and the interplay between photoinduced anisotropy and photoisomerization. © 2012 Wiley Periodicals, Inc.
Simulation of the π→π*photodynamics of azobenzene: decoherence and solvent effects.
Simplified treatment of organic substituents in SCF-CI calculations. The methyl group
The Journal of Chemical Physics
ABSTRACT
Stereochemical effects in the quenching of Na*(3 2P) by CO: Crossed beam experiment and ab initio CI potential energy surfaces
The Journal of Chemical Physics
ABSTRACT
The role of nonadiabatic coupling and sudden polarization in the photoisomerization of olefins
Journal of the American Chemical Society
ABSTRACT
Avoided crossing of molecular excited states and photochemistry: Butadiene and unprotonated Schiff base
International Journal of Quantum Chemistry
ABSTRACT
Coupled internal rotations in substituted ethoxybenzenes: Maximum entropy analysis of nuclear magnetic resonance of nematic solutions data and ab initio rotameric distributions
The Journal of Chemical Physics
ABSTRACT
A surface hopping study of energy transfer in $mboxNa + mboxCd^*$ collisions
Chemical Physics Letters
Short-time quantum dynamics of the driven rigid rotor
Zeitschrift für Physik D
ABSTRACT
Multiphoton absorption and phase correlation between driving field and molecular dipole
Journal of Physics B Atomic Molecular and Optical Physics
ABSTRACT
Theoretical study of $mboxNa(4mboxp^2mboxP)+mboxNa(3mboxs^2mboxS)$ and $mboxCd(5mboxp^3mboxP_0) +mboxNa(3mboxs^2mboxS)$ collisions and their role in the energy transfer between Cd$^*$ and Na
Chemical Physics Letters
We have studied the photofragmentation of azomethane by classical trajectories plus surface hoppi... more We have studied the photofragmentation of azomethane by classical trajectories plus surface hopping, run on ab initio potential energy surfaces. Transition probabilities are evaluated with the help of a general diabatization technique. The radiationless transition from S to S occurs within 0.5 ps and the fragmentation takes place almost exclusively in the 1 0 ground state. About 2r3 of the trajectories lead to almost simultaneous breaking of both N-C bonds, while 1r3 go through formation of the CH NN Ø radical; however, the latter breaks apart with a short delay of the order of 1 ps. q 1998 Elsevier 3 Science B.V. All rights reserved. 0009-2614r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 0 0 9 -2 6 1 4 9 8 0 0 4 0 2 -3
We review the field of computational studies of photochemistry in condensed phases, with particul... more We review the field of computational studies of photochemistry in condensed phases, with particular emphasis on the nonadiabatic dynamics of excited states. We examine methods for the determination of potential energy surfaces (PES) and other electronic properties in large systems, from clusters to liquids and crystals. The change of the PES with respect to the isolated molecule case is the most important item of the "static" environmental effects in photochemistry. "Dynamic" effects mainly consist in the transfer of energy and momentum from the chromophore or reactive center to the surrounding molecules. The interplay of internal processes, including the photoreaction, with thermalization and other more specific effects of chemical environment, can hardly be analyzed without the help of simulations of the excited state dynamics. A survey of methods and applications shows advantages and weaknesses of the basic choices offered by the state of the art: quantum wavepacket versus trajectory approaches, direct versus two-step dynamics, continuum versus explicit representations of the solvent.
NEWTON-X: a package for Newtonian dynamics close to the crossing seam
The determination of radial non-adiabatic coupling: HeNe 2+ as a case study
Journal of Physics B: Atomic and Molecular Physics, 1984
The matrix elements of the operator d/dR between the first three 1 Sigma + singlets of HeNe2+ hav... more The matrix elements of the operator d/dR between the first three 1 Sigma + singlets of HeNe2+ have been calculated by the rigorous finite differences technique and by Levy's projection method, based on the determination of the effective Hamiltonian in a quasi-diabatic basis. A numerical diabatisation procedure based on the knowledge of the d/dR matrix elements has also been applied.
Journal of Molecular Structure: THEOCHEM, 1985
The radial coupling between the first 'z+ states of HeNe2+ has been calculated in the adiabatic r... more The radial coupling between the first 'z+ states of HeNe2+ has been calculated in the adiabatic representation by means of the finite differences technique and in a non-adiabatic representation using a projection method previously developped.
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Papers by Maurizio Persico