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The electronic structure of nitrobenzene (C6H5NO2) has been studied by means of the complete active space self-consistent field (CASSCF) and multi-state second-order perturbation (MS-CASPT2) methods. To this end, an active space of 20 electrons distributed in 17 orbitals has been selected to construct the reference wave function. In this work, we have calculated the vertical excitation energies and the energy barrier for the dissociation of the molecule on the ground state into phenyl and nitrogen dioxide. After applying the corresponding vibrational corrections to the electronic energies, it is demonstrated that the MS-CASPT2//CASSCF values obtained in this work yield an excellent agreement between calculated and experimental data. In addition, other active spaces of lower size have been applied to the system in order to check the active space dependence in the results. UNIVERSIDAD DE MALAGA

The new class of oxide heterojunctions with mixed dimensionalities holds great promise for energy and environmental applications. However, the existing fabrication strategies typically involve low-yield and multistep processes leading to the formation of powders that necessitate binding agents when used for electrochemical applications; thereby, the durability and performance of the resultant electrode may be adversely impacted. To address these challenges, the present work first reports a high-temperature counter-current gas flow technique for rapid fabrication (5–10 min) of centimetre-size, self-adhesive, free-standing 3D patches made of ZnO-based woven nanowires. Furthermore, the high applicability of the method was shown by layer-by-layer assembly of the ZnO and layers of 0D heteroatoms including Bi2O3, CdO, SnO2, and carbon forming stratified oxide heterojunction (SOH) nanostructures with midgap states within their electronic bandgap region. This work is innovative in that the ZnO and the fabricated SOHs are synthesised through a sustainable and large-scale method based on microrecycling of waste materials. The engineering of the electronic band positions can modify the functionality of the SOH patches by optimising the potentials required for catalytic reactions. As a representative, the SOH nanostructures were tested for anodic electrocatalytic water oxidation to H2O2. The results showed that the ZnO–CdO patch has the lowest overpotential of 150 mV and outstanding stability at 2.33 V vs. RHE. Furthermore, the results of first-principles density functional theory (DFT) calculations (i) confirmed realignments of the band position due to the formation of midgap states, and (ii) revealed that significant improvements in the electrocatalytic H2O2 performance can be achieved with overpotentials as low as 0.19 and 0.31 V for ZnO–CdO and ZnO–Bi2O3, respectively. This work offers an ultrafast fabrication strategy to synthesise binder-free SOH nanostructures with an engineered electronic structure that can be an alternative to state-of-the-art noble metal electrocatalysts such as Pt.

International audience; The single-molecule magnet (SMM) properties of a series of ferrocenium complexes, [Fe(h5-C5R5)2]+ (R=Me, Bn), are reported. In the presence of an applied dc field, the slow dynamics of the magnetization in [Fe(h5-C5Me5)2]BArF are revealed. Multireference quantum mechanical calculationsshow a large energy difference between the ground and first excited states, excluding the commonly invoked, thermally activated (Orbach-like) mechanism of relaxation. In contrast, a detailed analysis of the relaxation time highlights that both direct and Raman processes are responsible forthe SMM properties. Similarly, the bulky ferrocenium complexes, [Fe(h5-C5Bn5)2]BF4 and [Fe(h5-C5Bn5)2]PF6, also exhibit magnetization slow dynamics, however an additional relaxation process is clearly detected for these analogous systems.

The ground state (GS) of Chichibabin's polycyclic hydrocarbons (CPHs) can be singlet (open- or closed-shell (OSS or CS)) or triplet (T), depending on the elongation of the π-system and the exocyclic substituents. CPHs with either a small singlet-triplet energy gap (ΔEST) or even a triplet GS have potential applications in optoelectronics. To analyze the effect of the size and exocy-clic substituents on the nature of the GS of CPHs, we have selected a number of them with different substituents in the exocyclic carbon atoms and different ring chain lengths. OPBE/cc-pVTZ level of theory was used for the optimization of the systems. The aromaticity of the resulting electronic structures was evaluated with HOMA, NICS, FLU, PDI, Iring, and MCI aromaticity indices. Our results show that the shortest π-systems (one or two rings) have a singlet GS. However, systems with three to five rings favor OSS GSs. Electron-withdrawing groups (EWGs) and aromatic substituents in the exocyclic carbons tend to stabilize the OSS and T states, while electron-donating groups slightly destabilize them. For CS, OSS, and T states, aromaticity measures indicate a gain of aromaticity of the six-membered rings of the CPHs with the increase in their size and when CPHs incorporate EWGs or aromatic substituents. In general, the CPHs analyzed present small singlet-triplet energy gaps, and in particular, the ones contain-ing EWGs or aromatic substituents present the smallest singlet-triplet energy gaps A.P. and M.S. thank the ́ Ministerio de Economi ́ a y Competitividad (MINECO) of Spain for projects CTQ2014-59832-JIN and CTQ2017-85341- P, Generalitat de Catalunya for project 2017SGR39, Xarxa de Referencia en Qui ̀ mica Teo ́ rica i Computacional, the ICREA ̀ Academia prize 2014 awarded to M.S., and European Fund for Regional Development (FEDER) grant UNGI10-4E-801

[ES] Dado su tamaño subnanométrico, los clusters metálicos están regidos por el confinamiento cuántico, lo que les hace más "moleculares" y menos "metálicos". En consecuencia, manifiestan propiedades que difieren con respecto a las de partículas más grandes del mismo elemento, y que a menudo son ventajosas para la catálisis de reacciones específicas. Además, su menor tamaño los hace más económicos, con una mayor superficie expuesta. Todo ello hace que los clusters sean opciones muy interesantes en catálisis, y su estudio, síntesis y aplicación ha crecido continuamente desde su descubrimiento en los años 90. Esta tesis se ha centrado principalmente en el cobre, del que se presenta, en primer lugar, un estudio fundamental sobre la disociación de oxígeno por clusters de diferentes tamaños. Después, se explora computacionalmente la catálisis de las oxidaciones de CO y propeno, confirmando que los clusters de Cu5 (o inferior) son prometedores para reacciones de oxidación. Las dos reacciones utilizadas son buenos ejemplos de la aplicación potencial en industria, sea para reducir emisiones de CO o para producir epóxido de propeno, que es un intermedio importante en la producción de plásticos y adhesivos, entre otros. Además, también se estudió la influencia de dos soportes en los clusters de cobre y su capacidad de oxidación: N-grafeno como un sistema más inerte y ceria como uno que puede participar activamente en reacciones de oxidación. Finalmente, se incluyen otros dos estudios más específicos, sobre la capacidad de los clusters de Pt3 y Pd3 para catalizar reaciones de acoplamiento C-C como la reacción de Heck, importante para la síntesis de productos de la química fina, y sobre la reacción CO + NO en clusters de Pt, motivado por su uso potencial como catalizadores para la conversión de esas especies en los menos perjudiciales CO2 y N2 en motores de combustión interna., [CA] Atès que són de grandària subnanomètrica, els clusters metàl·lics estan regits pel confinament quàntic, el qual els fa més "moleculars" i menys "metàl·lics". En conseqüència, manifesten propietats que són diferents a les de partícules més grans del mateix element, i que sovint són avantatjoses per a la catàlisi de reaccions específiques. A més a més, la seua menor grandària fa que siguen més econòmics, amb una major superfície exposada. Així, els clusters són una opció molt interesant en catàlisi, i el seu estudi, síntesi i aplicació ha cres-cut contínuament des del seu descobriment als anys 90. Aquesta tesi s'ha centrat principalment en el coure, del qual es presenta, en primer lloc, un estudi fonamental sobre la dissociació de l'oxígen per clusters de diferents grandàries. Després, s'explora computacionalment la catàlisi de les oxidacions de CO i de propè, confirmant que els clusters de Cu5 (o inferior) són prometedors per a reaccions d'oxidació. Les dues reaccions utilitzades són bons exemples de l'aplicació potencial en indústria, siga per reduir emissions de CO o per produir epòxid de propè, que és un intermedi important en la producció de plàstics i adhesius, entre altres. A més, també es va estudiar la influència de dos suports en els clusters de coure i la seua capacitat d'oxidació: N-grafè com a un sistema més inert i cèria com a un que pot participar activament en reaccions d'oxidació. Finalment, s'inclouen altres dos estudis més específics, sobre la capacitat dels clusters de Pt3 y Pd3 per catalitzar reaccions d'acoblament C-C com la reacció de Heck, important per a la síntesi de productes de la química fina, i sobre la reacció CO + NO als clusters de Pt, motivat pel seu ús potencial com a catalitzadors per a la conversió d'eixes espècies en els menys perjudicials CO2 i N2 als motors de combustió interna., [EN] Due to their subnanometric size, metal clusters belong to the regime affected by quantum confinement, which makes them more "molecular" and less "metallic". As a result, they exhibit properties that differ with respect to those of larger particles of the same element, and which are often advantageous in the catalysis of specific reactions. Besides, their smaller size makes them more economic and with a higher surface exposed. All of this renders metal clusters very interesting options for catalysis, and their study, synthesis and application has steadily increased since their discovery in the 90s. In this work we have largely focused on copper, of which a fundamental study on the oxygen dissociation by clusters of different sizes is first presented. Then, the catalysis of the CO and propene oxidation reactions is theoretically explored, confirming that Cu5 (or smaller) clusters are promising systems for oxidation reactions. The two reactions used are good examples of the potential application in industry, either to reduce CO emissions or to produce propene epoxide, an important intermediate in the production of plastics and adhesives, among others. In addition, the influence of two supports in the copper clusters and their oxidation capability is explored: on N-graphene as a more inert system and on ceria as one that can actively participate in oxidation reactions. Finally, two other more specific studies are included, regarding the capability of Pt3 and Pd3 clusters to undergo C-C coupling reactions such as the Heck reaction, important for the synthesis of many products of fine chemistry, and regarding the CO + NO reaction on Pt clusters, motivated by their potential use as catalysts for the conversion of those species in less harmful CO2 and N2 in internal combustion engines., En primer lugar me gustaría agradecer al Ministerio de Economía y Competitividad de España (MINECO) por la financiación de esta tesis mediante el programa Severo Ochoa (SVP-2013-068146), incluyendo los costes adicionales de mi estancia de investigación (EEBB-I-17-12057).

The electronic structure of AgCuO2, and more specifically the possible charge delocalization and its implications for the transport properties, has been the object of debate. Here the problem is faced by means of first-principles density functional theory calculations of the electron and phonon band structures as well as molecular dynamics simulations for different temperatures. It is found that both Cu and Ag exhibit noninteger oxidation states, in agreement with previous spectroscopic studies. The robust CuO2 chains impose a relatively short contact distance to the silver atoms, which are forced to partially use their dz2 orbitals to build a band. This band is partially emptied through overlap with a band of the CuO2 chain, which should be empty if copper were in a Cu3+ oxidation state. In that way, although structural correlations could roughly be consistent with an Ag+Cu3+O2 formulation, the appropriate oxidation states for the silver and copper atoms become Ag(1+δ)+ and Cu(3−δ)+, and as a consequence, the stoichiometric material should be metallic. The study of the electronic structure suggests that Ag atoms form relatively stable chains that can easily slide despite the linear coordination with oxygen atoms of the CuO2 chains. Phonon dispersion calculations and molecular dynamics simulations confirm the stability of the structure although pointing out that sliding of the silver chains is an easy motion that does not lead to substantial modifications of the electronic structure around the Fermi level and, thus, should not alter the good conductivity of the system. However, this sliding of the silver atoms from the equilibrium position explains the observed large thermal factors., This work was supported by MINECO (Spain) through Grant Nos. FIS2015-64886-C5-4-P, RTI2018-097753-B-I00, CTQ2015-64579-C3-3-P, and MAT2015-65192-R, Generalitat de Catalunya (2017SGR1506, 2017SGR1289, and XRQTC), and FONDECYT (Chile) through Project No. 11107163. E.C., N.C.-P., and A.G. acknowledge support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant No. SEV-2015-0496, and P.A. is supported from the Maria de Maeztu Units of Excellence Program under Grant No. MDM-2017-0767.

A 1 : 1 metallic charge-transfer salt is obtained by cosublimation of (Z,E)-(SMe)2Me2TTF and TCNQ. X-ray diffraction studies confirm the formation of segregated stacks comprising donor and acceptor molecules in [(E)-(SMe)2Me2TTF](TCNQ). The crystal packing features lateral S⋯S interactions between TTF stacks, which is in sharp contrast to that in (TTF)(TCNQ). Structural analysis and theoretical studies afford a partial charge-transfer (ρ ≈ 0.52), leading to a system with the electronic structure close to quarter-filled. Resistivity measurements reveal that this material behaves as a metal down to 56 K and 22 K at 1 bar and 14.9 kbar, respectively. The thermopower is negative in the metallic regime, indicating the dominant role of the acceptor stacks for the observed conducting behavior. Analysis of single-crystal EPR spectra shows the remaining spin susceptibility at 4.3 K, suggesting the importance of the Hubbard U correction. These results highlight the judicious engineering of electronic and geometrical effects on the TTF core; the combined use of methyl and thiomethyl groups has decreased the TCNQ bandwidth while maintaining the segregated stacks, converting the metal to insulator (M–I) transition to more 4kF like. In addition, the enhanced S⋯S contacts between the TTF stacks lead to more rapidly decreasing M–I transition temperature under various pressures., This research was supported by the French National Research Agency Grants, ANR 16-ACHN-0007 and ANR 17-ERC3-0003, and a PhD grant (to M. Beau) from the Bretagne region. Y. Kiyota is grateful to JSPS for a research fellowship (17J05098). We thank Dr A. Vacher (Rennes) for the preparation of (Z,E)-(SCH2CH2CN)2(Me)2TTF and CDIFX-Rennes for access to the X-ray diffractometer. Work in Spain was supported by MICIU (PGC2018-096955-B-C44 and PGC2018-093863-B-C22), MINECO through the Severo Ochoa (SEV-2015-0496) and Maria de Maeztu (MDM-2017-0767) Programs and the Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). Work in Japan was supported by JPSJ KAKENHI (Grant Number 16K13974 and 18H02044) and the Takahashi Industrial and Economic Research Foundation.

Producción Científica, Putative global minimum structures for neutral CdN and singly charged Cd+ N and Cd− N clusters in the small size regime up to N = 21 atoms are reported. A global optimization approach based on the basin hopping method and a Gupta potential fitted to cluster properties is employed to generate a diverse databank of trial structures, which are then re-optimized at the densityfunctional level of theory. Novel, previously unreported, structures are found for many sizes. Our results successfully reproduce and interpret the size-dependent stabilities known from mass spectrometry, and strongly suggest that experiments aimed at determining the relative stabilities of neutral cadmium clusters are really measuring cation stabilities. We provide an in-depth analysis of electronic structure and use it to explain the gradual emergence of metallic-like behaviour as the cluster size increases., Junta de Castilla y León (Project VA124G18), Ministerio de Ciencia, Innovación y Universidades (Project PGC2018-093745- B-100)

Despite B and Al belong to the same group 13 elements, the B6²- cluster prefers the planar D2h geometry, whereas Al6²- favours the Oh structure. In this work, we analyse the origin of the relative stability of the D2h and Oh forms in these clusters by means of an energy decomposition analysis based on the turn-upside-down approach. Our results show that what causes the different trend observed is the orbital interaction term, which combined with the electrostatic component do (Al6²- and Ga6²-) or do not (B6²-) compensate the higher Pauli repulsion of the Oh form. Analysing the orbital interaction term in more detail, we find that the preference of B6²- for the planar D2h form has to be attributed to two particular molecular orbital interactions. Our results are in line with a dominant delocalisation force in Al clusters and the preference for more localised bonding in B metal clusters. For mixed clusters, we have found that those with more than two B atoms prefer the planar structure for the same reasons as for B6²- This work has been supported by the Ministerio de Economía y Competitividad (MINECO) of Spain (Project CTQ2014-54306-P) and the Generalitat de Catalunya (project 2014SGR931, Xarxa de Referència en Química Teòrica i Computacional, ICREA Academia 2014 prize for M.S., and grant No. 2014FI_B 00429 to O.E.B.). The EU under the FEDER grant UNGI10-4E-801 (European Fund for Regional Development)has also funded this research. J. P. thanks the National Research School Combination - Catalysis (NRSCC), and The Netherlands Organization for Scientific Research (NWO/CW and NWO/NCF)

The key role of the molecular orbitals in describing electron transfer processes is put in evidence for the intervalence charge transfer (IVCT) of a synthetic nonheme binuclear mixed-valence Fe3+/Fe2+ compound. The electronic reorganization induced by the IVCT can be quantified by controlling the adaptation of the molecular orbitals to the charge transfer process. We evaluate the transition energy and its polarization effects on the molecular orbitals by means of ab initio calculations. The resulting energetic profile of the IVCT shows strong similarities to the Marcus' model, suggesting a response behaviour of the ensemble of electrons analogue to that of the solvent. We quantify the extent of the electronic reorganization induced by the IVCT process to be 11.74 eV, a very large effect that induces the crossing of states reducing the total energy of the transfer to 0.89 eV. © 2015 Wiley Periodicals, Inc.

Triarylmethyls (TAMs) are a class of long-lived purely organic radicals discovered at the beginning of the twentieth century. The chemical versatility and high stability of TAMs have lead to their application in many fields of science and technology. All compounds of this class are composed of three aryl rings bonded to a central carbon atom, where their unpaired electron mainly resides. Due to the π-conjugated electronic nature of this molecular structure, the possibility arises of controlling the unpaired electron localization (i.e. spin localization) by the torsion angles of the three aryl rings. By using density functional theory calculations (DFT) we have carefully investigated this phenomenon for a wide range of TAMs and probed how it is influenced by other important parameters such as chemical functionalization and temperature. Our results demonstrate that a single general spin versus structure relation is followed for all of our studied TAMs confirming that having a predictable structure-dependent spin localisation is an intrinsic feature of these radicals. Considering that spin localisation in TAMs is linked to many other important properties (e.g. magnetic interactions, optical absorption bands, magnetoresistance phenomena), the fact that manipulation of aryl ring twist angles could lead to molecular level control over such features presents enormous potential for future scientific and technological applications.

Quantum chemical calculations have unveiled the unexpected biradical character of titanium(IV) enolates from N-acyl oxazolidinones and thiazolidinethiones. The electronic structure of these species therefore involves a valence tautomerism consisting of an equilibrium between a closed shell (formally Ti(IV) enolates) and an open shell, biradical, singlet (formally Ti(III) enolates) electronic states, whose origin is to be basically found in changes of the Ti−O distance. Spectroscopic studies of the intermediate species lend support to such a model, which also turns out to be crucial for a better understanding of the overall reactivity of titanium(IV) enolates. In this context, a thorough computational analysis of the radical addition of titanium(IV) enolates from N-acyl oxazolidinones to TEMPO has permitted us to suggest an entire mechanism, which accounts for the experimental details and the diastereoselectivity of the process. All together, this evidence highlights the relevance of biradical intermediates from titanium(IV) enolates and may be a useful contribution to the foundations of a more insightful comprehension of the structure and reactivity of titanium(IV) enolates.

We have carried out first-principles total-energy calculations in order to study the electronic structure and thermodynamic properties of In 1-xBxP semiconducting alloys using the GGA and LDA formalisms within density functional theory (DFT) with a plane-wave ultrasoft pseudopotential scheme. We have also taken into account the correlation effects of the 3d-In orbitals within the LDA+U method to calculate the band-gap energy. We use special quasirandom structures to investigate the effect of the substituent concentration on structural parameter, band gap energy, mixing enthalpy and phase diagram of In1-xBxP alloys for x = 0, 0.25, 0.50, 0.75 and 1. It is found that the lattice parameters of the In 1-xBxP alloys decrease with B-concentration, showing a negative deviation from Vegard's law, while the bulk modulus increases with composition x, showing a large deviation from the linear concentration dependence (LCD). The calculated band structure presents a similar behavior for any B-composition using LDA, PBE or LDA+U approach. Our results predict that the band-gap shows a x-dependent nonlinear behavior. Calculated band gaps also shows a transition from (Γ→Γ)-direct to (Γ→Δ)- indirect at x = 0.611 and 0.566 for LDA and PBE functionals, respectively. Our calculations predict that the In1-xBxP alloy to be stable at unusual high temperature for both LDA and PBE potentials. © 2014 Elsevier B.V. All rights reserved. Hemos llevado a cabo cálculos de energía total de primeros principios para estudiar el Estructura electrónica y propiedades termodinámicas del semiconductor In 1-xBxP. aleaciones que utilizan los formalismos GGA y LDA dentro de la teoría funcional de la densidad (DFT) Con un esquema pseudopotencial ultrasoft de onda plana. También hemos tomado en cuenta los efectos de correlación de los orbitales 3d-In dentro del método LDA + U para calcular la energía de la brecha de banda. Usamos estructuras especiales cuasir aleatorias para investigar el efecto de la concentración de sustituyentes en el parámetro estructural, banda energía de separación, mezcla de entalpía y diagrama de fase de las aleaciones In1-xBxP para x = 0, 0.25, 0.50, 0.75 y 1. Se encuentra que los parámetros de red de las aleaciones In 1-xBxP disminuye con la concentración de B, mostrando una desviación negativa de la ley de Vegard, mientras que el módulo de volumen aumenta con la composición x, mostrando una gran desviación De la dependencia de la concentración lineal (LCD). La estructura de la banda calculada. presenta un comportamiento similar para cualquier composición B utilizando LDA, PBE o LDA + U enfoque. Nuestros resultados predicen que la brecha de banda muestra una no lineal dependiente de x comportamiento. Las brechas de banda calculadas también muestran una transición de (Γ → Γ) -directa a (Γ → Δ) - indirecto en x = 0.611 y 0.566 para las funciones LDA y PBE, respectivamente. Nuestros cálculos predicen que la aleación In1-xBxP se mantendrá estable en niveles inusuales Temperatura tanto para potenciales LDA como para PBE. © 2014 Elsevier B.V. Todos los derechos. reservado.

New insights into the double bond isomerization of fulvene in the ground and excited electronic states are provided by newly developed QTAIM and stress tensor tools. The S0 and S1 states follow the 'biradical' torsion model, but the double bond is stiffer in the S0 state; by contrast, the S2 state follows the 'zwitterionic' torsion. Differences are explained in terms of the ellipticity and bond critical point (BCP) stiffness for both QTAIM and the stress tensor. Overall, the wave-function based analysis is found to be in agreement with the work of Bonačić-Koutecký and Michl that the bond-twisted species can have biradical or zwitterionic character, depending on the state. Using QTAIM and the stress tensor a new understanding of bond torsion is revealed; the electronic charge density around the twisted bond is found not to rotate in concert with the nuclei of the rotated -CH2 methylene group. The ability to visualize how the bond stiffness varies between individual electronic states and how this correlates with the QTAIM and stress tensor bond stiffness is highlighted. In addition, the most and least preferred morphologies of bond-path torsion are visualized. Briefly we discuss the prospects for using this new QTAIM and stress tensor analysis for excited state chemistry The One Hundred Talents Foundation of Hunan Province and the aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province are gratefully acknowledged for the support of S.J. and S. R. K. The National Natural Science Foundation of China is also gratefully acknowledged for the support of S.J. and S. R. K, project approval number: 21273069. L. B. acknowledges support from the Spanish Ministerio de Economia y Sostenibilidad (MINECO) (CTQ2011-26573 and UNGI08-4E-003 from FEDER (European Fund for Regional Development)), and the Catalan Agencia de Gestio d'Ajuts Universitaris i de Recerca (SGR0528) and Direccio General de la Recerca (Xarxa de Referencia en Quimica Teorica i Computacional de Catalunya)

The electronic structure of main-group diatomic molecules is discussed in the light of local spin analysis. A deep investigation into the origin of local spins and their coupling is presented. It is shown that the presence of significant local spins in bonded molecules flags deviations from the classical bonding prototypes. For the notorious example of the C2 molecule, the local spin analysis indicates that its ground state has all ingredients to be categorized as a diradical. Is C2 a diradical? Local spin analysis is used to discuss the electronic structure of main-group diatomic molecules. The presence of significant local spins in bonded molecules flags deviations from the classical bonding prototypes, that is, the extent of local spin is a measure of the deviation of a bond from perfect covalent character (see figure). The results indicate that the C2 molecule in its ground state has all the ingredients to be categorized as a diradical Financial help has been furnished by the Spanish MICINN Projects No. CTQ2011-23441/BQU and CTQ2011-23156/BQU. Financial support from MICINN and the FEDER fund (European Fund for Regional Development) was also provided by grant UNGI08-4E-003. Financial support from the Generalitat de Catalunya (SGR528 and Xarxa de Referencia en Quimica Teorica i Computacional) is also acknowledged. E. R-C. acknowledges support from the Spanish FPU program (Grant No. AP2008-01231). M. R. is grateful to ETH Zurich and the Swiss National Science Foundation (SNF) for financial support

We carried out a theoretical study on the structural stability, elastic, electronic and thermodynamic properties of the Sc x Ga 1− x P compound ( x = 0, 0.25, 0.50, 0.75 and 1) in the ZnS and NaCl crystallographic phases. For this purpose, we performed ab initio calculations using the DFT within LDA and GGA approximations. To solve the Kohn-Sham equations, we implemented the accurate full-potential linearized augmented plane wave method. From the results obtained, it can be noted that for the 0≤ x ≤0.30 range, the most stable structure of Sc x Ga 1− x P is the ZnS phase, and for the 0.30 x ≤1 interval, the most stable structure is the NaCl phase. The structural results also show a phase transition from the ZnS to NaCl at a pressure of ∼ 2.84 GPa for a Sc concentration value of 25%. Electronic band structure analysis shows that in the ZnS phase, for a 25% of Sc concentration, Sc x Ga 1− x P is a direct semiconductor, and from 50% to 100% concentrations in the NaCl phase, the compound exhibits a metallic behavior. Calculated phase diagrams predict Sc x Ga 1− x P to be stable as homogeneous alloy phases at high temperature for both ZnS and NaCl phases.

Interactions between transition metal nanoparticles and reducible oxide supports are thought to significantly affect the performance of many catalysts. Usually, several metal-support effects act together and cannot be separated from each other. Herein, by means of density-functional calculations we succeeded to single out and quantify effects of the metal-support electron transfer on the structure and electronic properties of important model Pt-ceria catalysts. Namely, we considered ∼1.5 nm large Pt 95 and Pt 122 particles supported on CeO 2 (1 1 1). We show that Pt-ceria interactions notably reconstruct Pt nanofacets forming the interface and shift valence d-states of the Pt particles. These effects are rather insensitive to the Pt-ceria electron transfer, at variance with the electronic structure of oxygen anions at the interface, which is significantly affected by the electron transfer. The findings of this work and the special modeling approach applied pave the way for deeper analysis of electronic metal-support interactions in catalysis.

We report two new single‐ion magnets (SIMs) of a family of oxydiacetate lanthanide complexes with D3 symmetry to test the predictive capabilities of complete active space ab initio methods (CASSCF and CASPT2) and the semiempirical radial effective charge (REC) model. Comparison of the theoretical predictions of the energy levels, wave functions and magnetic properties with detailed spectroscopic and magnetic characterisation is used to critically discuss the limitations of these theoretical approaches. The need for spectroscopic information for a reliable description of the properties of lanthanide SIMs is emphasised. SPINMOL ERC-CoG-647301 DECRESIM MAT2014-56143-R CTQ2014-52758-P CTQ2011-23861-C02-01 CTQ2015-64579-C3-1-P MDM-2015-0538 We report two new single‐ion magnets (SIMs) of a family of oxydiacetate lanthanide complexes with D3 symmetry to test the predictive capabilities of complete active space ab initio methods (CASSCF and CASPT2) and the semiempirical radial effective charge (REC) model. Comparison of the theoretical predictions of the energy levels, wave functions and magnetic properties with detailed spectroscopic and magnetic characterisation is used to critically discuss the limitations of these theoretical approaches. The need for spectroscopic information for a reliable description of the properties of lanthanide SIMs is emphasised.

Electronic structure calculations have been performed on four different Mn corrole and corrolazine complexes to clarify the role of the imide axial ligand on the relative stability of the different spin states and the stabilization of the high valent Mn ion in these complexes. Multiconfigurational perturbation theory energy calculations on the DFT optimized geometries shows that all complexes have a singlet ground state except the complex with the strongest electron withdrawing substituent on the imide axial ligand, which is found to have a triplet ground state. The analysis of the sigma and pi interaction between metal and imide ligand shows that this spin crossover is caused by a subtle interplay of geometrical factors (Mn-N distance and coordination angle) and the electron withdrawing character of the substituent on the imide, which reduces the electron donation to the metal centre. The analysis of the multiconfigurational wave functions reveals that the formally MnV ion is stabilized by an important electron transfer from both the equatorial corrole/corrolazine ligand and the axial imide. The macrocycle donates roughly half an electron, being somewhere between the closed-shell trianionic and the dianionic radical form. The imide ligand transfers 2.5 electrons to the metal center, resulting in an effective d-electron count close to five in all complexes.

Filiació URV: SI Electronic structure calculations have been performed on four dierent Mn corrole and corrolazine complexes to clarify the role of the imide axial ligand on the relative stability of the dierent spin states and the stabilization of the high valent Mn ion in these complexes. Multicongurational perturbation theory energy calculations on the DFT optimized geometries shows that all complexes have a singlet ground state except the complex with the strongest electron with- drawal axial ligand, which is found to have a triplet ground state. The analysis of the sigma and pi interaction between metal and imide ligand shows that this spin crossover is caused by a subtle interplay of geometrical factors (Mn-N distance and coordination angle) and the electron withdrawal character of the imide. The analysis of the multicongurational wave functions reveals that the formally MnV ion is stabilized by an important electron transfer from both the equatorial cor-role/corrolazine ligand and the axial imide. The macrocycle donates roughly half an electron, being somewhere between the closed-shell trianionic and the dian-ionic radical form. The imide ligand transfers 2.5 electrons to the metal center, resulting in an eective d-electron count close to ve in all complexes.

In this paper, aluminum tungstate Al2(WO4)3 powders were synthesized using the co-precipitation method at room temperature and then submitted to heat treatment processes at different temperatures (100, 200, 400, 800, and 1000 °C) for 2 h. The structure and morphology of the powders were characterized by means of X-ray diffraction (XRD), Rietveld refinement data, and field emission scanning electron microscopy (FE-SEM) images. Their optical properties were examined with ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy and photoluminescence (PL) measurements. XRD patterns and Rietveld refinement data showed that Al2(WO4)3 powders heat treated at 1000 °C for 2 h have a orthorhombic structure with a space group (Pnca) without the presence of deleterious phases. FE-SEM images revealed that these powders are formed by the aggregation of several nanoparticles leading to the growth of microparticles with irregular morphologies and an agglomerated nature. UV–vis spectra indicated that optical band gap energy increased from 3.16 to 3.48 eV) as the processing temperature rose, which was in turn associated with a reduction in intermediary energy levels. First-principle calculations were performed in order to understand the behavior of the PL properties using density functional theory at the B3LYP calculation level on periodic model systems and indicate the presence of stable electronic excited states (singlet). The analyses of the band structures and density of states at both ground and first excited electronic states provide insight into the main features, based on structural and electronic order–disorder effects in octahedral [AlO6] clusters and tetrahedral [WO4] clusters, as constituent building units of this material. The Brazilian authors acknowledge the financial support of the Brazilian research financing institutions: CNPq (304531/2013-8), FAPESP (09/50303-4; 12/18597-0), and CAPES. The Spanish authors would like to thank the Spanish Government MAT2010-21088-C03 project and the Catalan Government PIGC project 2009-SGR-0674. J. Andrés acknowledges Generalitat Valenciana (Prometeo/2009/053 project), Ministerio de Ciencia e Innovación (CTQ-2012-36253-C03-01) Programa de Cooperación Científica con Iberoamerica (Brazil), Ministerio de Educación (PHB2009-0065-PC project).

Collisions between potassium ions and neutral i-C3H7Br and i-C3H7OH, all in their electronic ground state, have been studied in the 0.10-10.00 eV center of mass (CM) collision energy range, using the radiofrequency-guided ion beam technique. In K(+) + i-C3H7Br collisions KHBr(+) formation was observed and quantified, while the analogous KH2O(+) formation in K(+) + i-C3H7OH was hardly detected. Moreover, formation of the ion-molecule adducts and their decomposition leading to C3H7(+) and either KBr or KOH, respectively, have been observed. For all these processes, absolute cross-sections were measured as a function of the CM collision energy. Ab initio structure calculations at the MP2 level have given information about the potential energy surfaces (PESs) involved. In these, different stationary points have been characterized using the reaction coordinate method, their connectivity being ensured by using the intrinsic-reaction-coordinate method. From the measured excitation function for KHBr(+) formation the corresponding thermal rate constant at 303 K has been calculated. The topology of the calculated PESs allows an interpretation of the main features of the reaction dynamics of both systems, and in particular evidence the important role played by the potential energy wells in controlling the reactivity for the different reaction channels.

The optical and electrical recovery processes of the metastable state of the EL2 defect artificially created in n‐type GaAs by boron or oxygen implantation are analyzed at 80 K using optical isothermal transient spectroscopy. In both cases, we have found an inhibition of the electrical recovery and the existence of an optical recovery in the range 1.1–1.4 eV, competing with the photoquenching effect. The similar results obtained with both elements and the different behavior observed in comparison with the native EL2 defect has been related to the network damage produced by the implantation process. From the different behavior with the technological process, it can be deduced that the electrical and optical anomalies have a different origin. The electrical inhibition is due to the existence of an interaction between the EL2 defect and other implantation‐created defects. However, the optical recovery seems to be related to a change in the microscopic metastable state configuration involving the presence of vacancies.

In the present work, an analysis of the dark and optical capacitance transients obtained from Schottky Au:GaAs barriers implanted with boron has been carried out by means of the isothermal transient spectroscopy (ITS) and differential and optical ITS techniques. Unlike deep level transient spectroscopy, the use of these techniques allows one to easily distinguish contributions to the transients different from those of the usual deep trap emission kinetics. The results obtained show the artificial creation of the EL2, EL6, and EL5 defects by the boron implantation process. Moreover, the interaction mechanism between the EL2 and other defects, which gives rise to the U band, has been analyzed. The existence of a reorganization process of the defects involved has been observed, which prevents the interaction as the temperature increases. The activation energy of this process has been found to be dependent on the temperature of the annealing treatment after implantation, with values of 0.51 and 0.26 eV for the as‐implanted and 400 °C annealed samples, respectively. The analysis of the optical data has corroborated the existence of such interactions involving all the observed defects that affect their optical parameters.

An analysis of silicon on insulator structures obtained by single and multiple implants by means of Raman scattering and photoluminescence spectroscopy is reported. The Raman spectra obtained with different excitation powers and wavelengths indicate the presence of a tensile strain in the top silicon layer of the structures. The comparison between the spectra measured in both kinds of samples points out the existence in the multiple implant material of a lower strain for a penetration depth about 300 nm and a higher strain for higher penetration depths. These results have been correlated with transmission electron microscopy observations, which have allowed to associate the higher strain to the presence of SiO2 precipitates in the top silicon layer, close to the buried oxide. The found lower strain is in agreement with the better quality expected for this material, which is corroborated by the photoluminescence data.

An extension of the spin density functional theory simultaneously accounting for dielectric mismatch between neighboring materials and nonparabolicity corrections originating from interactions between conduction and valence bands is presented. This method is employed to calculate ground state and addition energy spectra of homogeneous and multishell spherical quantum dots. Our calculations reveal that corrections become especially relevant when they come into play simultaneously in strong regimes of spatial confinement.

The computational approach to the Hirshfeld [Theor. Chim. Acta 44, 129 (1977)] atom in a molecule is critically investigated, and several difficulties are highlighted. It is shown that these difficulties are mitigated by an alternative, iterative version, of the Hirshfeld partitioning procedure. The iterative scheme ensures that the Hirshfeld definition represents a mathematically proper information entropy, allows the Hirshfeld approach to be used for charged molecules, eliminates arbitrariness in the choice of the promolecule, and increases the magnitudes of the charges. The resulting Hirshfeld-I charges correlate well with electrostatic potential derived atomic charges

Selected configuration interaction (SCI) for atomic and molecular electronic structure calculations is reformulated in a general framework encompassing all CI methods. The linked cluster expansion is used as an intermediate device to approximate CI coefficients B(K) of disconnected configurations (those that can be expressed as products of combinations of singly and doubly excited ones) in terms of CI coefficients of lower-excited configurations where each K is a linear combination of configuration-state-functions (CSFs) over all degenerate elements of K. Disconnected configurations up to sextuply excited ones are selected by Brown's energy formula, Delta E(K) = (E-H(KK))B(K)2/(1-B(K)2), with B(K) determined from coefficients of singly and doubly excited configurations. The truncation energy error from disconnected configurations, Delta E(dis), is approximated by the sum of Delta E(K)s of all discarded Ks. The remaining (connected) configurations are selected by thresholds based on natural orbital concepts. Given a model CI space M, a usual upper bound E(S) is computed by CI in a selected space S, and E(M) = E(S) + Delta E(dis) + delta E, where delta E is a residual error which can be calculated by well-defined sensitivity analyses. An SCI calculation on Ne ground state featuring 1077 orbitals is presented. Convergence to within near spectroscopic accuracy (0.5 cm(-1)) is achieved in a model space M of 1.4 x 10(9) CSFs (1.1 x 10(12) determinants) containing up to quadruply excited CSFs. Accurate energy contributions of quintuples and sextuples in a model space of 6.5 x 10(12) CSFs are obtained. The impact of SCI on various orbital methods is discussed. Since Delta E(dis) can readily be calculated for very large basis sets without the need of a CI calculation, it can be used to estimate the orbital basis incompleteness error. A method for precise and efficient evaluation of E(S) is taken up in a companion paper.

Se presenta la capacidad de las técnicas de modelización molecular basadas en métodos de la química cuántica para predecir la estructura molecular y electrónica de polímeros conductores. Concretamente, se discute la aplicabilidad de estas herramientas computacionales al estudio de diferentes aspectos del politiofeno y sus derivados: geometría molecular y planaridad, cambios estructurales producidos por el dopado, propiedades electrónicas y desarrollo de nuevos materiales conductores.

In this work, the aromatic fluctuation index (FLU) that describes the fluctuation of electronic charge between adjacent atoms in a given ring is introduced as a new aromaticity measure. This new electronic criterion of aromaticity is based on the fact that aromaticity is related to the cyclic delocalized circulation of pi electrons. It is defined not only considering the amount of electron sharing between contiguous atoms, which should be substantial in aromatic molecules, but also taking into account the similarity of electron sharing between adjacent atoms. For a series of rings in 15 planar polycyclic aromatic hydrocarbons, we have found that, in general, FLU is strongly correlated with other widely used indicators of local aromaticity, such as the harmonic-oscillator model of aromaticity, the nucleus independent chemical shift, and the para-delocalization index (PDI). In contrast to PDI, the FLU index can be applied to study the aromaticity of rings with any number of members and it can be used to analyze both the local and global aromatic character of rings and molecules.

Oxygen vacancies in metal oxides are known to determine their chemistry and physics. The properties of neutral oxygen vacancies in metal oxides of increasing complexity (MgO, CaO, alpha-Al2O3, and ZnO) have been studied using density functional theory. Vacancy formation energies, vacancy-vacancy interaction, and the barriers for vacancy migration are determined and rationalized in terms of the ionicity, the Madelung potential, and lattice relaxation. It is found that the Madelung potential controls the oxygen vacancy properties of highly ionic oxides whereas a more complex picture arises for covalent ZnO.

We report two new analytical fits of the ground potential energy surface (PES) (2A') and the first excited PES (4A') involved into the title reaction and its reverse, using ab initio electronic structure calculations from papers I and II along with new grids of ab initio points by means of the Second-Order Perturbation Theory on CASSCF wave function (CASPT2 (17,12) G2/aug-cc-pVTZ) reported here (1250 points for the 2A' PES and 910 points for the 4A' PES). Some experimental data were also introduced to better account for the exoergicity and the experimental rate constant at 300 K. The final root-mean-square deviations of the fits were 1.06 and 1.67 kcal/mol for 2A' and the 4A' PESs, respectively, for the NOO Cs-abstraction and insertion regions of the PESs. Thermal rate constants were calculated (300-5000 K) for both the direct and reverse reactions by means of the variational transition state theory with the inclusion of a microcanonical optimized multidimensional tunneling correction, obtaining a very good agreement with the experimental data within all the temperature range. The new analytical 2A' PES presents several stationary points not introduced in previous analytical surfaces, and describes accurately the NO2 (X 2A1) minimum, which seems to be very accessible according to the trajectories run in a preliminary quasiclassical trajectory study. The new analytical 4A' PES has a lower energy barrier than the previous one, which increases significantly the contribution of this PES to the total rate constant at high temperatures. Moreover, the new analytical PESs not only describe accurately the Cs-regions of the NOO system but also the ONO C2v- or near C2v-regions.

Recent improvements in the determination of the running of the fine-structure constant also allow an update of the hadronic vacuum-polarization contribution to the Lamb shift. We find a shift of -3.40(7) kHz to the 1S level of hydrogen. We also comment on the contribution of this effect to the determination by elastic electron scattering of the r.m.s. radii of nuclei., Comment: 7 pages, latex, 1 figure -- Submitted to Phys. Rev. A -- epsfig.sty required

The synthesis and structural characterization at room temperature and 130 K of the organic charge-transfer salt bis(thiodimethylene)-tetrathiafulvalene tetracyanoquinodimethane (BTDMTTF-TNCQ) is reported. X-ray diffuse scattering as well as ir and Raman measurements show that the charge transfer in this salt is ∼0.5. BTDMTTF-TCNQ remains metallic down to very low temperatures but exhibits an anomaly at 175 K in the conductivity and thermopower which could be related to some unusual structural modification of the unit cell. Band-structure calculations show that this salt is a narrow-band one-dimensional metal. The high value of the spin susceptibility, the low value of the conductivity, and the observation of a 4 k F charge-density-wave (CDW) instability around room temperature prove that it is a highly correlated metal. In contrast with other salts of the TTF-TCNQ family, BTDMTTF-TCNQ does not exhibit critical 2 k F structural fluctuations. It is proposed that the absence of the 2 k F CDW transition is due to the stronger interlocking of the donor and acceptor molecules due to the presence of the sulfur atoms in the central position of the outer five-membered rings of the BTDMTTF donor.

The nature of the chemical bond in three titanium oxides of different crystal structure and different formal oxidation state has been studied by means of the ab initio cluster-model approach. The covalent and ionic contributions to the bond have been measured from different theoretical techniques. All the analysis is consistent with an increasing of covalence in the TiO, ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{TiO}}_{2}$ series as expected from chemical intuition. Moreover, the use of the ab initio cluster-model approach combined with different theoretical techniques has permitted us to quantify the degree of ionic character, showing that while TiO can approximately be described as an ionic compound, ${\mathrm{TiO}}_{2}$ is better viewed as a rather covalent oxide.

In this work, we demonstrate that conductive atomic force microscopy (C-AFM) is a very powerful tool to investigate, at the nanoscale, metal-oxide-semiconductor structures with silicon nanocrystals (Si-nc) embedded in the gate oxide as memory devices. The high lateral resolution of this technique allows us to study extremely small areas ( ~ 300nm2) and, therefore, the electrical properties of a reduced number of Si-nc. C-AFM experiments have demonstrated that Si-nc enhance the gate oxide electrical conduction due to trap-assisted tunneling. On the other hand, Si-nc can act as trapping centers. The amount of charge stored in Si-nc has been estimated through the change induced in the barrier height measured from the I-V characteristics. The results show that only ~ 20% of the Si-nc are charged, demonstrating that the electrical behavior at the nanoscale is consistent with the macroscopic characterization.

Filiació URV: SI The key role of the molecular orbitals in describing electron transfer processes is put in evidence for the intervalence charge transfer (IVCT) of a synthetic non-haem binuclear mixed-valence Fe3+/Fe2+ compound. The electronic reorganization induced by the IVCT can be quantified by controlling the adaptation of the molecular orbitals to the charge transfer process. We evaluate the transition energy and its polarization e¿ects on the molecular orbital by means of ab initio calculations. The resulting energetic profile of the IVCT shows strong similarities to the Marcus¿ model, suggesting a response behaviour of the ensemble of electrons analogue to that of the solvent. We quantify the extent of the electronic reorganization induced by the IVCT process to be 11.74 eV, a very large e¿ect that induces the crossing of states reducing the total energy of the transfer to 0.89 eV.

Filiació URV: SI Density functional theory, Complete Active Space Self-Consistent Field (CASSCF) and perturbation theory (CASPT2) methodologies have been used to explore the electronic structure of a series of trichromium Extended Metal Atom Chains (EMACS) with different capping ligands. The study is motivated by the very different structural properties of these systems observed in X-ray experiments: the CN−-capped example has a symmetric Cr3 unit while for the NO3−-capped analogue the same unit has two very different Cr–Cr bond lengths. Density functional theory fails to locate an unsymmetric minimum for any of the systems studied, although the surface corresponding to the asymmetric stretch is very flat. CASPT2, in contrast, does locate an unsymmetric minimum only for the NO3−-capped system, although again the surface is very flat. We use the Generalized active space (GASSCF) technique and effective Hamiltonian theory to interrogate the multi-configurational wavefunctions of these systems, and show that the increase in the σ–σ* separation as the chain becomes unsymmetric plays a defining role in the stability of the ground state and its expansion in terms of configuration state functions.

Zinc indium tin oxide (ZITO) transparent conductive oxide layers were deposited via radio frequency (RF) magnetron co-sputtering at room temperature. A series of samples with gradually varying zinc content was investigated. The samples were characterized with x-ray and ultraviolet photoemission spectroscopy (XPS, UPS) to determine the electronic structure of the surface. Valence and conduction bands maxima (VBM, CBM), and work function were determined. The experiments indicate that increasing Zn content results in films with a higher defect rate at the surface leading to the formation of a degenerately doped surface layer if the Zn content surpasses ∼50%. Furthermore, the experiments demonstrate that ZITO is susceptible to ultraviolet light induced work function reduction, similar to what was earlier observed on ITO and TiO2 films.

Filiació URV: SI Electronic structure calculations have been performed on four dierent Mn corrole and corrolazine complexes to clarify the role of the imide axial ligand on the relative stability of the dierent spin states and the stabilization of the high valent Mn ion in these complexes. Multicongurational perturbation theory energy calculations on the DFT optimized geometries shows that all complexes have a singlet ground state except the complex with the strongest electron with- drawal axial ligand, which is found to have a triplet ground state. The analysis of the sigma and pi interaction between metal and imide ligand shows that this spin crossover is caused by a subtle interplay of geometrical factors (Mn-N distance and coordination angle) and the electron withdrawal character of the imide. The analysis of the multicongurational wave functions reveals that the formally MnV ion is stabilized by an important electron transfer from both the equatorial cor-role/corrolazine ligand and the axial imide. The macrocycle donates roughly half an electron, being somewhere between the closed-shell trianionic and the dian-ionic radical form. The imide ligand transfers 2.5 electrons to the metal center, resulting in an eective d-electron count close to ve in all complexes.

The electronic structure and chemical bonding in donor-acceptor complexes formed by group 13 element adamantine and perfluorinated adamantine derivatives EC9Rʹ15 (E = B, Al; R´= H, F) with Lewis bases XR3 and XC9H15 (X=N, P; R= H, CH3) have been studied using energy decomposition analysis (EDA) at the BP86/TZ2P level of theory. Larger stability of complexes with perfluorinated adamantine derivatives is mainly due to better electrostatic and orbital interactions. Deformation energies of the fragments and Pauli repulsion are of less importance, with exception for the boron-phosphorus complexes. The MO analysis reveals that LUMO energies of EC9Rʹ15 significantly decrease upon fluorination (by 4.7 and 3.6 eV for E = B and Al, respectively) which results in an increase of orbital interaction energies by 27-38 (B) and 15-26 (Al) kcal mol-1. HOMO energies of XR3 increase in order PH3 < NH3 < PMe3 < PC9H15 < NMe3 < NC9H15. For the studied complexes, there is a linear correlation between the dissociation energy of the complex and the energy difference between HOMO of the donor and the LUMO of the acceptor molecules. The fluorination of the Lewis acid significantly reduces standard enthalpies of the heterolytic hydrogen splitting H2 + D + A = [HD]+ + [HA]-. Analysis of the several types of the [HD]+ ··[HA]- ion pair formation reveals that orientation with additional H···F interactions is the most favorable energetically. Taking into account the ion pair formation, hydrogen splitting is predicted to be highly exothermic in case of the perfluorinated derivatives. Thus, fluorinated adamantine-based Lewis superacids are attractive synthetic targets and good candidates for the construction of the donor-acceptor cryptands This work was financially supported by St. Petersburg State University research grant 12.50.1194.2014. Excellent service of the Centre de Serveis Científiics i Acadèmmics de Catalunya (CESCA) and computer cluster at St. Petersburg State University is gratefully acknowledged. J.P. thanks the Netherlands Organization for Scientific Research (NWO-CW, NWO-EW, NWO-ALW) for financial support. M. S. thanks the following organizations for financial support: the Spanish government (MINECO, project number CTQ2014-54306-P), the Generalitat de Catalunya (project number 2014SGR931, ICREA Academia 2014 prize for excellence in research, and Xarxa de Referència en Química Teòrica i Computacional), and the FEDER fund (European Fund for Regional Development) for the grant UNGI10-4E-801

The electronic structure of the wurtzite-type phase of aluminum nitride has been investigated by means of periodic ab initio Hartree-Fock calculations. The binding energy, lattice parameters (a,c), and the internal coordinate (u) have been calculated. All structural parameters are in excellent agreement with the experimental data. The electronic structure and bonding in AlN are analyzed by means of density-of-states projections and electron-density maps. The calculated values of the bulk modulus, its pressure derivative, the optical-phonon frequencies at the center of the Brillouin zone, and the full set of elastic constants are in good agreement with the experimental data.