A5009734644- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
- Machine Learning in Materials Science
- Photoreceptor and optogenetics research
- Advanced Electron Microscopy Techniques and Applications
- Photochromic and Fluorescence Chemistry
- Molecular Junctions and Nanostructures
- Catalysis and Oxidation Reactions
- Advanced X-ray Imaging Techniques
- Supramolecular Self-Assembly in Materials
- Atomic and Subatomic Physics Research
- Crystallization and Solubility Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Electron Spin Resonance Studies
- Spectroscopy and Laser Applications
- Force Microscopy Techniques and Applications
- Organometallic Complex Synthesis and Catalysis
- Organic Light-Emitting Diodes Research
- Nonlinear Optical Materials Studies
- Advanced MRI Techniques and Applications
- Adhesion, Friction, and Surface Interactions
- Molecular spectroscopy and chirality
- Photochemistry and Electron Transfer Studies
- Catalytic Cross-Coupling Reactions
University of Bologna
2019-2025
The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in stable branch package or via interfaces other packages. These span wide range topics computational and presented thematic sections: electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features. This report offers an overview chemical phenomena processes can...
We have used state-of-the-art ab initio restricted active RASPT2 computations using a 16 orbitals, 18 electrons space to produce an extended three-dimensional map of the potential energy surfaces (PESs) ground and first nπ* excited states azobenzene along CNNC torsion two CNN bending angles, which are most relevant coordinates for trans-cis photoisomerization process. Through comparison with fully unconstrained optimizations performed at same level theory, we show that three selected suffice...
X-ray diffraction is routinely used for structure determination of stationary molecular samples. Modern photon sources, e.g., from free-electron lasers, enable us to add temporal resolution these scattering events, thereby providing a movie atomic motions. We simulate and decipher the various contributions pattern femtosecond isomerization azobenzene, textbook photochemical process. A wealth information encoded besides real-time monitoring charge density cis trans isomerization. In...
This work demonstrates how push–pull substitution can induce spectral tuning toward the visible range and improve photoisomerization efficiency of azobenzene-based photoswitches, making them good candidates for technological biological applications. The red-shifted bright ππ* state (S2) behaves like lower more productive dark nπ* (S1) because less potential energy along planar bending mode is available to reach higher unproductive nπ*/S0 crossing regions, which are responsible quantum yield...
We present an accurate and efficient approach to computing the linear nonlinear optical spectroscopy of a closed quantum system subject impulsive interactions with incident electromagnetic field. It incorporates effect ultrafast nonadiabatic dynamics by means explicit numerical propagation nuclear wave packet. The fundamental expressions for evaluation first- higher-order response functions are recast in general form that can be used any code capable overlap packets evolving different...
Conical intersections directly mediate the internal energy conversion in photoinduced processes a wide range of chemical and biological systems. Because Brillouin theorem, many conventional electronic structure methods, including configuration interaction with single excitations from Hartree-Fock reference time-dependent density functional theory either linear response approximation (TDDFT) or Tamm-Dancoff (DFT-TDA), have wrong dimensionality for conical between ground state (S0) first...
Conical intersections directly mediate the internal energy conversion in photoinduced processes a wide range of chemical and biological systems. Because Brillouin theorem, many conventional electronic structure methods, including configuration interaction with single excitations from Hartree-Fock reference time-dependent density functional theory either linear response approximation (TDDFT) or Tamm-Dancoff (DFT-TDA), have wrong dimensionality for conical between ground state (S0) first...
With this work, we present a protocol for the parameterization of Linear Vibronic Coupling (LVC) Hamiltonian quantum dynamics using highly accurate multiconfigurational electronic structure methods such as RASPT2/RASSCF, combined with maximum-overlap diabatization technique. Our approach is fully portable and can be applied to many medium-size rigid molecules whose excited state requires description. We our model discuss details calculations needed parameterization, analyzing critical...
Conical intersections (CoIns) play an important role in ultrafast relaxation channels. Their monitoring remains a formidable experimental challenge. We theoretically compare the probing of S2 → S1 CoIn passage 4-thiouracil by its vibronic coherences, using off-resonant X-ray-stimulated Raman spectroscopy (TRUECARS) and time-resolved X-ray diffraction (TRXD). The quantum nuclear wavepacket (WP) dynamics provides accurate picture photoinduced dynamics. Upon photoexcitation, WP oscillates among...
In this article the recent developments of open-source OpenMolcas chemistry software environment, since spring 2020, are described, with main focus on novel functionalities that accessible in stable branch package and/or via interfaces other packages. These community span a wide range topics computational chemistry, and presented thematic sections associated electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features....
A novel 1,2-azaborine (i.e., 4-methyl-2-(pyridin-2-yl)-2,1-borazaronaphthalene, 1a) has been synthesized and used for the first time as a B-N alternative to common cyclometalating ligands obtain neutral phosphorescent iridium(III) complexes 2a, 3, 4) of general formula [Ir(C∧N)2(N∧NB)], where C∧N indicates three different (Hppy = 2-phenylpyridine; Hdfppy 2-(2,4-difluoro-phenyl)pyridine; Hpqu 2-methyl-3-phenylquinoxaline). Moreover, azaborine-based complex 2a was compared isoelectronic C═C...
We study the ultrafast time evolution of cyclobutanone excited to singlet n → Rydberg state through non-adiabatic surface-hopping simulationsperformed at extended multi-state complete active space second-order perturbation (XMS-CASPT2) level theory. These dynamics predict relaxation ground-state with a timescale 822 ± 45 fs minimal involvement triplets. The major path involves three-state degeneracy region and leads variety fragmented photoproducts. simulate resulting time-resolved...
Significance Monitoring the real-space motion of electrons directly involved in ultrafast molecular dynamics is a challenging goal, hindered by strong contributions remaining inactive electrons. Molecular quantum coherences can provide direct window into elementary electronic dynamics, but they could not be separately imaged so far. Here, we demonstrate time- and frequency-resolved X-ray diffraction technique, which employ existing stochastic pulses to image coherence contributions. The...
In this work, we show how the structural features of photoactive azobenzene derivatives can influence photoexcited state behavior and yield trans/cis photoisomerization process. By combining high-resolution transient absorption experiments in vis–NIR region quantum chemistry calculations (TDDFT RASPT2), address origin signals three poly-substituted push–pull azobenzenes with an increasing strength intramolecular interactions stabilizing planar trans isomer (absence H-bonds, methyl,...
We demonstrate how two-photon excitation with quantum light can influence elementary photochemical events. The azobenzene
The fate of virtually all photochemical reactions is determined by conical intersections. These are energetically degenerate regions molecular potential energy surfaces that strongly couple electronic states, thereby enabling fast relaxation channels. Their direct spectroscopic detection relies on weak features often buried beneath stronger, less interesting contributions. For azobenzene photoisomerization, a textbook reaction, we demonstrate how resonant infrared field can be employed...
Ultrafast electron diffraction is a powerful technique that can resolve molecular structures with femtosecond and angstrom resolutions. We demonstrate theoretically how it be used to monitor conical intersection dynamics in molecules. Specific contributions the signal are identified which vanish absence of vibronic coherence offer direct window into paths. A special focus on hybrid scattering from nuclei electrons, process unique (rather than X-ray) monitors strongly coupled nuclear...
Artificial molecular motors are at the forefront of research in nanotechnology due to their ability perform tasks by harnessing directionally controlled motion scale. In particular, development light-driven nanomotors is a challenging task that nonetheless holds great potential for sunlight-powered systems and active materials. Herein, we describe novel azoimidazolium photochemical rotary motor which operates along triangular reaction cycle taking advantage formation diastereomeric species...
An efficient screening of azobenzene (AB) derivatives for Molecular Solar Thermal (MOST) applications based on ground state properties (energy stored per molecule and Z isomer stability) could be performed with...
In this article the recent developments of open-source OpenMolcas chemistry software environment, since spring 2020, are described, with main focus on novel functionalities that accessible in stable branch package and/or via interfaces other packages. These community span a wide range topics computational chemistry, and presented thematic sections associated electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features....
Expressions for linear and nonlinear spectroscopy simulation in the X-ray window which time evolution of a photoexcited molecular system is treated via quantum dynamics are derived. By leveraging on peculiar properties core-excited/ionized states, first- third-order response functions recast limit time-scale separation between extremely short core-state lifetime (comparably longer) electronic-state transfer nuclear vibrational motion. This work natural extension Segatta et al. (J. Chem....
Time-resolved X-Ray diffraction signals are simulated to monitor the ultrafast photoisomerization of azobenzene, a textbook photophysical process. Different signal contributions, with special focus on scattering from coherences emerging at conical intersection, discussed.