197,033 research outputs found
A Time Averaged Semiclassical Approach to IR Spectroscopy
No full textSemiclassical vibrational spectroscopy is based on the evolution of classical trajectories and is able to reproduce quantum effects with good accuracy at the cost of a reasonable computational effort. [1-5] Nevertheless, semiclassical vibrational power spectra do not simulate all the features of the experimental IR spectra, since intensities in power spectra are not directly related to IR absorptions. Therefore, we
developed a new semiclassical approach to the calculation of molecular IR spectra by employing the time average technique upon symmetrization of the quantum dipole-dipole autocorrelation function. [6,7] We tested the accuracy of this new method on a few simple analytical systems and small molecules in the gas phase. In particular, spectra in the limit of infinite or zero temperature were investigated. Overall the method features excellent accuracy in calculating absorption intensities and provides estimates for the frequencies of vibrations in agreement with the corresponding power spectra.
[1] R. Conte, A. Aspuru-Guzik, and M. Ceotto, J. Phys. Chem. Lett. 4, 3407 (2013).
[2] G. Bertaina, G. Di Liberto, and M. Ceotto, J. Chem. Phys. 151, 114307 (2019).
[3] C. Aieta, M. Micciarelli, G. Bertaina, and M. Ceotto, Nat. Comm. 11, 4384 (2020).
[4] A. Rognoni, R. Conte, and M. Ceotto, Chem. Sci. 12, 2060 (2021).
[5] R. Conte, C. Aieta, G. Botti, M. Cazzaniga, M. Gandolfi, C. Lanzi, G. Mandelli, D. Moscato, and M. Ceotto, Theor. Chem. Acc. 142, 53 (2023).
[6] A. L. Kaledin and W. H. Miller, J. Chem. Phys. 118, 7174 (2003).
[7] A. L. Kaledin and W. H. Miller, J. Chem. Phys. 119, 3078 (2003)
Recensione a M. Rossi, Le fila del tempo. Il sistema di Luigi Lanzi, Olschki, Firenze, 2006
No full textRecensione a M. Rossi, Le fila del tempo. Il sistema di Luigi Lanzi, Olschki, Firenze, 200
Comparison of Tm-sensitized Ho:YAG and Ho:YLF crystals for a laser-pumped 2 mu m CW oscillator
No full textWe report on a comparison of YAG and YLF crystals for Tm,Ho based CW laser systems operating at 2 mu m. As pump source we have used both a Ti:Al2O3 laser and an array of diode lasers in order to quantitatively assess the relevance of the pump beam spatial features on the 2 mu m laser performance. The results are compared with the predictions of a computer simulation using a rate equation model
An extended semiclassical initial value representation approach to IR spectroscopy
No full textRecently—Lanzi et al., J. Chem. Phys. 160, 214107 (2024)—we introduced a time averaged approach to infrared (IR) spectroscopy. The pivotal advance in that paper was represented by the possibility to get accurate semiclassical estimates of the IR absorption intensities and associated transition frequencies from a single calculation. However, the method relies on the convergence of Monte Carlo integrations based on the generation of thousands of pairs of semiclassical trajectories. This makes the approach highly accurate but limited to small, few-atom molecules. Here, we build on the theoretical grounds of that work to extend the application of the method to larger molecules. The goal is achieved by moving to tailored single-pair trajectory calculations and introducing a partially time-independent approximation to the real part of the coherent state overlap. Upon testing the level of accuracy on small molecules such as water, formaldehyde, and methane, we
calculate IR spectra for ethanol and glycine. Vibrational intensities and frequencies are found to be fairly accurate, and the method can be straightforwardly applied to larger molecular systems
Fuzzy tactics: A scripting game that leverages fuzzy logic as an engaging game mechanic
No full textArtificial intelligence (AI) plays a major role in modern video games by making them feel both more realistic and more fun to play. Game intelligence usually works alongside the game logic, in the background, invisible to the players who enjoy the resulting character behaviors, the adaptive gameplay, and the procedurally generated content. However, artificial intelligence can also have a central role and become a major component of the overall gameplay (as for instance in the video game Black & White).
In this paper, we define the genre of scripting video games and introduce Fuzzy Tactics, a video game we developed that has an innovative gameplay based on fuzzy logic and uses fuzzy rules as its core game mechanic and user interaction mechanism. In Fuzzy Tactics, players lead their troops into battle by specifying a set of fuzzy rules that determines the battle behavior of the units. Fuzzy logic is the only mean that players have to interact with the game and to command to their troops. Thus, it becomes the main game mechanic that allows us to (i) extend the depth of the game, (ii) keep the interaction intuitive, while also (iii) increasing the replayability and the educational value of the game
Efficient and thermally stable BHJ solar cells based on a soluble hydroxy-functionalized regioregular polydodecylthiophene
No full textA new regioregular polythiophene derivative, called poly[3-(12-hydroxydodecyl)thiophene] (PT12OH), was synthesized by post-functionalizing its ω-brominated precursor poly[3-(12-bromododecyl)thiophene] (PT12Br) prepared using the Grignard metathesis route. Thanks to the optimal balance between hydrophilic and hydrophobic groups within its structure, PT12OH was highly soluble and easily filmable from common organic solvents allowing for its complete characterization. It also showed enhanced thermal properties, crystallinity, and self-assembling capabilities by the formation of strong inter- and intrachain hydrogen bonds. Bulk heterojunction photovoltaic cells with PT12OH and PC61BM showed a PCE of 4.83% and a remarkable over-time stability, offering good photoconversion efficiency even after 120 h of accelerated aging. Indeed, the PCE decrease was 34% for the hydroxylated polymer and 65% for its brominated precursor. It should also be pointed out that the enhanced thermal stability of PT12OH was achieved without resorting to any complex post-annealing photochemical, thermal, or chemical treatment and was thus directly ascribable to the polymer chemical structure. The simple and effective synthetic procedure, photovoltaic efficiency, and enhanced stability revealed the potential of PT12OH for large-scale organic solar cell applications
Recent Advances in the Synthesis and Polymerization of New CO2-Based Cyclic†
No full textCarbon dioxide can be converted into functional heterocycles known as cyclic carbonates, whose recent reactivity has been expanded towards the formation of tailor-made engineering polymers. This minireview gives an overview of the most topical developments in this area with a special focus on the synthetic methods employed to prepare these CO2 based synthons. In addition, their application potential in the area of polymer science using a variety of polymerization techniques is discussed that have in common the ring-opening of the carbonate monomers. Future perspectives are provided that provide impetus for the scientific communities aligning research to the use of sustainable processes for polymers from recyclable carbon sources such as CO2
ADHOC: a tool for performing effective feature selectionProceedings Eighth IEEE International Conference on Tools with Artificial Intelligence
No full textThe paper introduces ADHOC, a tool that integrates statistical methods and machine learning techniques to perform effective feature selection. Feature selection plays a central role in the data analysis process since redundant and irrelevant features often degrade the performance of induction algorithms, both in speed and predictive accuracy. ADHOC combines the advantages of both filter and feedback approaches to feature selection to enhance the understanding of the given data and increase the efficiency of the feature selection process. We report results of extensive experiments on real world data which demonstrate the effectiveness of ADHOC as data reduction technique as well as feature selection method. ADHOC has been employed in the analysis of several corporate databases. In particular, it is currently used to support the difficult task of early estimation of the cost of software projects
Semiclassical vibrational spectroscopy from small molecules to solvated biomolecules
No full textThe hallmark of semiclassical dynamics is the ability to get quantum effects starting from classical
trajectories.[1] Therefore, the main challenge semiclassical methods have to face is to demonstrate
their accuracy and possibility to be applied even to large and complex systems.[2]
I will show that semiclassical dynamics can be straightforwardly interfaced to different descriptions
of the potential energy surface (PES), ranging from ab initio PESs[3-5] to force fields[6,7] and
QM/MM schemes. This allows one to apply semiclassical spectroscopy to the calculation of the
quantum vibrational features of very different systems, including not only small molecules
characterized by elusive Fermi resonances, like ethanol, or hard-to-assign experimental spectra, like
proline, but also large systems like solvated biomolecules. Finally, ongoing efforts to reproduce also
the intensity of absorption in the framework of semiclassical dynamics will be illustrated.[8]
[1] W. H. Miller The semiclassical initial value representation: A potentially practical way for
adding quantum effects to classical molecular dynamics J. Phys. Chem. A 105, 2942 (2001).
[2] M. Ceotto, G. Di Liberto, R. Conte Semiclassical “divide-and-conquer” method for
spectroscopic calculations of high dimensional molecular systems Phys. Rev. Lett. 119, 010401
(2017).
[3] R. Conte, A. Nandi, C. Qu, Q. Yu, P. L. Houston, and J. M. Bowman Semiclassical and
VSCF/VCI calculations of the vibrational energies of trans- and gauche-ethanol using a CCSD(T)
potential energy surface J. Phys. Chem. A 126, 7709 (2022).
[4] A. Rognoni, R. Conte, M. Ceotto Caldeira-Leggett model vs ab initio potential: A vibrational
spectroscopy test of water solvation J. Chem. Phys. 154, 094106 (2021).
[5] G. Botti, C. Aieta, R. Conte The complex vibrational spectrum of proline explained through the
adiabatically switched semiclassical initial value representation J. Chem. Phys. 156, 164303 (2022).
[6] F. Gabas, R. Conte, M. Ceotto Quantum vibrational spectroscopy of explicitly solvated
thymidine in semiclassical approximation J. Phys. Chem. Lett. 13, 1350 (2022).
[7] D. Moscato, F. Gabas, R. Conte, M. Ceotto Vibrational spectroscopy simulation of solvation
effects on a G-quadruplex J. Biomol. Struct. Dyn. doi:10.1080/07391102.2023.2180435 (2023).
[8] C. Lanzi, C. Aieta, M. Ceotto, R. Conte A semiclassical approach to IR spectroscopy, being
prepared
Diaryl hypervalent bromines and chlorines: synthesis, structures and reactivities
No full textIn the field of modern organic chemistry, hypervalent compounds have become indispensable tools for synthetic chemists, finding widespread applications in both academic research and industrial settings. While iodine-based reagents have historically dominated this research field, recent focus has shifted to the potent yet relatively unexplored chemistry of diaryl lambda 3-bromanes and -chloranes. Despite their unique reactivities, the progress in their development and application within organic synthesis has been hampered by the absence of straightforward, reliable, and widely applicable preparative methods. However, recent investigations have uncovered innovative approaches and novel reactivity patterns associated with these specialized compounds. These discoveries suggest that we have only begun to tap into their potential, implying that there is much more to be explored in this captivating area of chemistry.Diaryl hypervalent bromines and chlorines emerge as a novel foundation for advancing organic chemistry. This article provides an overview of the synthetic methodology, structural variations, and the latest transformations unearthed in this context
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