196,621 research outputs found
Guareschi, gli Internati Militari Italiani e il «Diario clandestino»
No full textIl ruolo di Guareschi nei campi di concentramento degli IMI e l'importanza testimoniale del «Diario clandestino
Poster P15: Excited states of molecular solutes with Quantum Monte Carlo: vertical transition and geometry optimization
No full textRecently, we have developed a novel Polarizable Continuum Model (PCM), which includes both surface and volume polarization of the dielectric medium (pure SVPE scheme), designed for the Quantum Monte Carlo (QMC) treatment of the solute. In particular, the treatment of volume polarization, due to quantum mechanical penetration of the solute charge density in the solvent domain, is based on quantum Monte Carlo techniques. The method allows to accurately solve Poisson's equation of the solvation model coupled with the Schrödinger equation for the solute [1,2,3]. The present model has been now extended to treat the effects of solvation in solute vertical electronic transitions and to the search of the solute equilibrium geometry in the excited states. For the first case, here we show the results of our study
performed on fast n → pi* and pi → pi* vertical transitions of s-trans- acrolein in water [4]. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we have added a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. The calculated solvatochromic shifts are properly described. For the second case, we start from recent
advances made to carry out the ground- and excited-state geometry optimization within QMC [5]. For the present purpose, we have extended the calculation of the forces to include solvent e_ects through our QMC implementation of PCM [6]. We show results, performed at the variational Monte Carlo level, on the excited-state geometry optimization of some small organic molecules in water solution and we make a comparison with the more widely used TDDFT and CASPT2 methods.
[1] C. Amovilli, C. Filippi, F. M. Floris, J. Phys. Chem. B (2006) 110 26225.
[2] C. Amovilli, C. Filippi, F. M. Floris, J. Chem. Phys. (2008) 129 244106.
[3] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2012) 137 075102.
[4] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2014) 140 034109.
[5] R. Guareschi, C. Filippi, J. Chem. Theor. Comput. (2013) 9 5513.
[6] R. Guareschi, F. M. Floris, C. Amovilli, C. Filippi, in preparation (2014)
Icilio Guareschi and his amazing “1897 reaction”
No full textOrganic chemistry honors Icilio Guareschi (1847-1918) with three eponymic reactions, the best known ones being the Guareschi synthesis of pyridones and the Guareschi-Lustgarten reaction. A third Guareschi reaction, the so-called “Guareschi 1897 reaction”, is one of the most unusual reactions in organic chemistry, involving the radical-mediated paradoxical aerobic generation of hydrocarbons in near-neutral water solution. A discussion of the mechanism of this amazing reaction, the only metal-free process that generates hydrocarbons, and the implications of the approach in biology and geosciences mirrors the multifaceted scientific personality of the discoverer. Thus, Guareschi's eclectic range of activities spans a surprising variety of topics, overcoming the boundaries of the traditional partition of chemistry into organic, inorganic, and analytical branches and systematically crosses the divide between pure and applied science as well as between the history of chemistry and the personal contributions to its development
Guareschi: il mondo in duecento parole?
No full textPartendo da una confessione autobiografica di Guareschi, e col riscontro di varie pagine estratte soprattutto dalla serie del "Mondo Piccolo", si definisce ed esemplifica la lingua guareschiana, cólta e popolare nello stesso tempo, su espliciti modelli manzoniani
Chi decide? Critica della ragione eccezionalista
No full textUna critica del ricorso alla categoria di eccezione come chiave di lettura privilegiata delle politiche di emergenza del presente, a partire dalla geografia multiscalare dei processi globali e dalla ridefinizione delle forme e delle prerogative della sovranità statale
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