Patricio F. Provasi's research while affiliated with National University of the Northeast and other places

... 0.01, and 3.40 eV, respectively. The lower HOMO-LUMO gaps indicate that these complexes may have enhanced NLO response as observed by Fonseca et al. in their work on NLO response of chromophores[62]. ...

... They are the simplest objects among short oligopeptides, thus, are very attractive for investigation by experimental and computer simulation methods. The tautomerization and the pH dependence of glycine and glycine containing oligopeptides were widely investigated by various theoretical [16][17][18][19][20][21][22] and experimental (capillary electrophoresis, potentiometry, IR and UV spectroscopy, THz spectroscopy, EPR spectroscopy, etc.) methods [23,24], including NMR spectroscopy [25][26][27][28][29][30][31]. Previously, it was shown that chemical shifts [32] and 1 J CαH one bond spin-spin coupling constants (SSCC) [33] of amino acid residues in various (backbone, C-or N-terminal) positions in peptides are different. ...

... A time-independent magnetic field induces toroidal electron flow in chiral molecules [1][2][3][4][5][6][7][8], giving rise to a static toroidal moment, which can be represented by a vector odd under charge conjugation C, parity P and time reversal T. The optical fields associated with a beam of monochromatic light, oscillating with frequency ω, also induce the anapolar response, which can be rationalized in terms of dynamic anapole polarizabilities and magnetizabilities [9]. ...

... Since the first implementation of ASEC, a variety of molecular properties have been studied and, according to the results, parameters such as the nuclear magnetic constants, [21][22][23][24][25] as well as the convergence of electronics excitation spectra of chromophore [26,27] are strongly affected by solvent polarization. However, despite these advances, a discussion on how the NLO parameters can be affected by the redistribution of electronic charges in the solute molecule is lacking. ...

... Most recently, Eriksen et al. [22,23] presented the PCM-SOPPA/RPA solvent model (described in Section 2.2) and applied it to the calculation of excitation energies in a water environment. The results showed that the PCM-SOPPA/RPA calculations had a tendency to underestimate the excitation energies compared with experimental values, as is also observed in gas phase SOPPA calculations [24,25]. Different solvent models have also been combined with density functional theory (DFT) for calculations of spin-spin coupling constants. ...

... I. As the constitutive molecular properties that account for the manifestation of magnetic anapoles are dipole-quadrupole and quadrupole-quadrupole magnetizabilities, [73][74][75]81 in the first place, we review the theoretical state-of-the-art, outlining and extending the results of previous investigations [82][83][84][85] into the anapolar response of a molecule to time-independent magnetic fields, based on time-independent Rayleigh-Schrödinger perturbation theory (RSPT) 86,87 and alternative powerful procedures, allowing for a nonperturbative approach and basis sets of London orbitals, [88][89][90][91] which have also been applied to evaluate the relevant tensors. 68,70,92 To enquire into the more general case of optical anapoles 64,93,94 for molecules in the presence of optical fields, time-dependent perturbation theory 95 has been applied to determine a set of dynamic anapole susceptibilities in Sec. ...

... Our benchmark set was chosen based on the availability of good experimental data and keeping the size of the selected molecules small to reduce the computational effort. For the SSCC calculations, five different methods were used: SOPPA [28][29][30][31], HRPA(D) [32] and DFT with the functionals B3LYP [33,34], BHandH [34,35], and PBE0 [36,37]. ...

... The PBE0/pcJ-1 level had satisfactory agreement with the obtained experimental J FH SSCC, being used in the remaining SSCCs calculations. The calculation of through-space SSCC involving fluorine was also recently studied by Sauer et al., [39][40][41] and the authors reported that PBE0 was the functional of best performance, which is in agreement with what we observed in this paper. The calculated SSCC reproduces the behavior of the experimental SSCC: as the solvent polarity increases, the trans-TFT conformer becomes more populated (Table S5, ESI †). ...

... DFT) [83,104,105]. For DFT approaches, the factors that significantly affect the accuracy of predicted 13 C and/or 1 H NMR chemical shifts are the optimization level of molecular geometry [106][107][108], the use of different DFT theories [109][110][111][112], implicit and explicit solvation models [113][114][115], unique molecular properties of metabolites [116][117][118][119][120][121], etc. Agreement between predicted and experimental chemical shifts can be improved when (i) the basis set is enlarged [104,122], (ii) the quality of the method is improved for geometry optimization [123,124], (iii) a scaling procedure is employed [125,126], (iv) conformational sampling is applied [127], and (v) solvation is taken into account appropriately [128,129]. However, the question of what level of accuracy is required for calculated NMR chemical shifts when using these as reference spectra for molecular identification remains largely unexplored. ...

... Hence, the proton transfer of the neutral glycine, stable in the gas phase, to zwitterionic conformer, stable in aqueous solution, has an estimated free energy barrier of about 7.3 kcal mol [1][2][3]5,6,8,[10][11][12][13][14]. Some other recent works aim to study small clusters of Glycine: (H 2 O) n complexes in order to elucidate structures and binding energies [15][16][17][18], or the stabilization of Z-Glycine in water and its NMR signature [19] and the election of a method for fast accurate of 1 J(C, H) for application in proteins [20]. ...