The micro-hydration of
Zn
2
+
was studied for clusters growing from 6 to 216 water molecules to derive the zinc coordination number as a function of cluster size and temperature and to bridge the gap ...between recent experimental values determined in the gas phase and in solution. The increasing complexity of potential energy surfaces requires extensive exploration, which was addressed using polarizable molecular dynamics with extended time frames. Reliable coordination numbers have been obtained for the different cluster sizes, at temperatures ranging from 200 to 300 K. The results provide a global picture of a growing coordination number as a function of cluster size, from ca. 5 for small gaseous clusters to 6 in bulk water.
High-harmonic generation (HHG) is used to produce coherent XUV and soft X-ray radiation with attosecond resolution and is a sensitive tool for probing atomic and molecular structures. In this work, ...we have used time-dependent configuration interaction with a Gaussian basis set to compute the HHG spectrum of the hydrogen atom. To get a correct description of the HHG optical spectrum, the Gaussian basis set has to provide an accurate representation of the bound and the continuum states. Two strategies have been proposed: (1) multicentered (defining ghost atoms around the hydrogen) and (2) optimal-continuum Gaussian basis sets. We have systematically investigated these two approaches for the hydrogen atom, which permits a non-biased analysis of the basis set. Several basis sets have been constructed and tested by combining multicentered and optimal-continuum functions together in order to obtain a reliable and accurate Gaussian basis set to be used for HHG. We have studied the effect of changing the number of ghost atoms and the distance between the ghosts and the hydrogen atom, with and without optimal-continuum Gaussian functions. We conclude that multicentered basis sets are less efficient than basis sets using only optimal-continuum Gaussian functions for a proper description of HHG.
This book places the discourse surrounding stigmata within the visual culture of the late medieval and early modern periods, with a particular focus on Italy and on female stigmatics. Echoing, and to ...a certain extent recreating, the wounds and pain inflicted on Christ during his passion, stigmata stimulated controversy. Related to this were issues that were deeply rooted in contemporary visual culture such as how stigmata were described and performed and whether, or how, it was legitimate to represent stigmata in visual art. Because of the contested nature of stigmata and because stigmata did not always manifest in the same form - sometimes invisible, sometimes visible only periodically, sometimes miraculous, and sometimes self-inflicted - they provoked complex questions and reflections relating to the nature and purpose of visual representation.
The adsorption of trivalent arsenic As(OH)
3
onto the bimetallic Au
19
Cu and Au
19
Pd clusters was computationally studied to get insights about as embedded electrodes with bimetallic gold ...nanostructures can serve for the adsorption and subsequent sensing of arsenic traces from polluted waters. It was found that the As(OH)
3
chemisorption onto Au
19
Cu and Au
19
Pd is reached with adsorption energies of up to 1.02 and 1.48 eV, respectively, with even a stable physisorption with energies of up to 0.57 eV. Both arsenic and oxygen atoms were determined to bind with adsorbent Cu and Pd atoms, and all the interactions appear to be stable in an aqueous environment. The stability of the adsorbent–pollutant interactions was explained in terms of metal–pollutant chemical binding, charge transfer, dispersion force interactions and non-conventional OH···Au hydrogen bonds. Moreover, the As(OH)
3
adsorption on the metal clusters is also accompanied by changes in the reactivity, electron transfer and decreases of the HOMO–LUMO energy gap with respect to the isolated substrates; the highest changes obtained in the mentioned properties are classified in the order Au
19
Pd > Au
19
Cu > Au
20
.
We studied the influence of relativistic and electron correlation effects on NMR J-couplings in the following set of heavy-atom containing molecules:
X
Y
4
and H
3
X
X
H
3
(
X
= Sn, Pb;
Y
= H, F, Cl, ...Br, I). We applied two formalisms, the relativistic polarization propagator approach at random phase level of approach (RelPPA-RPA) and density functional theory (DFT) with functionals as implemented in the DIRAC code. We have chosen four functionals that have different amount of HF exchange (PBE0, B3LYP, BLYP, BP86). For those molecular systems, results of calculations with BLYP functional have the best performance as compared with available experimental data. As was previously found for magnetic shieldings in other molecular systems we are able to show here that DFT functionals must be modified in order to obtain reliable results of NMR J-coupling within the relativistic regime. We can state that there is a non-linear dependence among both, electron correlation and relativistic effects that should be introduced in the functionals. The functionals implemented in the DIRAC code are standard nonrelativistic ones which were parameterized with data taken from light-atom containing molecules. This explains why they are not able to properly introduce relativistic effects on NMR parameters, like J-coupling constant. Lastly we show that in the analysis of J-couplings for the family of compounds mentioned above, one must consider the effects of a third heavy-atom that is close to the J-coupled atoms of the same molecule, specially for
n
J(H–H). This kind of effect is similar to the newest and so called heavy-atom effect on vicinal heavy atoms, HAVHA, proposed for the NMR-shielding constant. Such effects are among the most important relativistic effects in the family of compounds studied in this work.
The developing of fluorescent probes for disease diagnosis is a very important task, which favors precision in the diagnosis and success in the treatment. Recently, amino-naphthoquinone derivatives ...showed to be efficient fluorescent probes for disease diagnosis. Those compounds exhibit excited-state intramolecular proton transfer (ESIPT), which is the main mechanism responsible for their use as fluorescent probes. The understanding of the ESIPT mechanism for naphthoquinones is an important way of developing more efficient and selective fluorescent probes. In this work, the ESIPT process for ANQ was performed at the TD-DFT/CAM-B3LYP/DGTZVP and DFT/B3LYP/DGTZVP level for the electronic and geometric studies. These parameters were selected for the PCA analysis. The solvent effect was investigated by using PCM and IEF-PCM in chloroform, water and methanol. 2-Amino-1,4-naphthoquinone (ANQ) showed blue emission for fluorescence, having keto–keto* absorption at 4.50 eV and the enol–enol* decay at 2.75 eV. The solvent effect was evaluated, and the ESIPT process of ANQ was favorable in nonpolar and polar solvents. Furthermore, the thermodynamics properties showed that the ESIPT is favorable with a proton transfer equilibrium constant of ~10
5
.
This contribution focuses on bulk band gap and dielectric response calculations for copper phosphide Cu
3
P, using hybrid functionals and linear response DFT+U methods, considering both plane wave ...and Gaussian-type orbitals basis sets. The semiconducting state of Cu
3
P is reproduced in good quantitative agreement with experiments when using these methods, at variance with the description provided by standard DFT calculations based on GGA functionals, predicting Cu
3
P to be a semimetal. Additional DFT+U calculations were performed on zinc blende cadmium selenide CdSe, to further investigate the effect of
U
on semiconducting binary compounds. For both Cu
3
P and CdSe, the materials’ band gap depends strongly on the on-site repulsion of the nonmetal unfilled
p
-orbitals, while hybrid functionals still perform well. This suggests that the use of the Hubbard term in DFT+U calculations should be carefully checked for all elements when dealing with semiconducting binary compounds.
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