Sr_{2}Fe_{1.5}Mo_{0.5}O_{6−δ} (SFMO) is a promising electrode material for solid oxide electrochemical cells. This perspective highlights the role of first-principles investigations in unveiling SFMO structural, electronic, and defect properties. In particular, DFT + U provides a reliable and convenient tool for extensive studies on strongly correlated transition-metal oxides, as SFMO and related systems. The SFMO excellent performances are ascribed to a mixed oxide ion-electron conductor character. Crucial features are the easy formation of oxygen vacancies and the low oxide migration barrier heights. Aliovalent doping with K^{+} enables convenient hydration and effective proton transport in bulk SFMO. This opens a route toward new promising triple-conductor oxides. Besides discussion of specific SFMO applications, our results help to uncover general perovskite-oxide features and new design principles for oxide- and proton-conducting solid oxide fuel cell electrodes. © 2016 Wiley Periodicals, Inc.

Quantum-chemical investigations can boost the development of advanced materials for energy conversion technologies. In the context of solid oxide fuel cells, the case of Sr_{2}Fe_{1.5}Mo_{0.5}O_{6−δ}-based electrodes exemplifies the successful application of DFT methods to the rational design of triple-conductor oxides, highlighting the key structure–property–function relationships that determine the oxide and proton bulk transport processes in perovskite oxides.

The possible noncovalent lone pair-π/halogen bond (lp···π/HaB) complexes of perhalogenated unsaturated C_{2}Cl_{n}F_{4−n} (*n* = 0–4) molecules with four simple molecules containing oxygen or nitrogen as electron donor, formaldehyde (H_{2}CO), dimethyl ether (DME), NH_{3}, and trimethylamine (TMA), have been systematically examined at the M062X/aug-cc-pVTZ level. Natural bond orbital (NBO) analysis at the same level is used for understanding the electron density distributions of these complexes. The progressive introduction of Cl atom on C_{2}Cl_{n}F_{4−n} influences more on the lp···π complexes over the corresponding HaB ones. Within the scope of this study, gem-C_{2}Cl_{2}F_{2} is the best partner molecule for lp···π interaction with the simple molecules, coupled with the greatest interaction energy (IE) and second-order orbital interaction [*E*(2) value], whereas C_{2}F_{4} is the poorest one. The C_{2}Cl_{3}F·H_{2}CO and C_{2}Cl_{4}·H_{2}CO complexes exhibit reverse lp···π bonding, while the Z/E-C_{2}Cl_{2}F_{2}·NH_{3}, C_{2}Cl_{3}F·NH_{3} and C_{2}Cl_{4}·NH_{3} complexes perform half-lp···π bonding according to the NBO analysis. The lp···π interaction involving the oxygen/nitrogen and the π-hole of C_{2}Cl_{n}F_{4−n} overwhelms the HaB involving the oxygen/nitrogen and the σ-hole of the Cl atom. The electron-donating methyl groups contribute significantly to the two competitive interactions, therefore, DME and TMA engage stronger in the partner molecules than H_{2}CO and NH_{3}. Our theoretical study would be useful for future experimental investigation on noncovalent complexes. © 2016 Wiley Periodicals, Inc.

Complexes of chlorofluorocarbons (freons) with oxygen/nitrogen containing simple molecules are studied as models of noncovalent interaction. The possible noncovalent lone pair-π/halogen bond (lp···π/HaB) complexes of formaldehyde, dimethyl ether, ammonia and trimethylamine with perhalogenated unsaturated C_{2}Cl_{n}F_{4−}_{n} (*n* = 0–4) molecules have been systematically examined at the M062X/aug-cc-pVTZ level. For these model systems, the lp···π interaction overwhelms the halogen bond, and gem-C_{2}Cl_{2}F_{2} is the best partner molecule for lp···π interaction with the simple molecules.

It is shown that the Pauli potential in bound Coulomb systems can in good approximation be composed from the corresponding atomic fragments. This provides a simple and fast procedure how to generate the Pauli potential in bound systems, which is needed to perform an orbital-free density functional calculation. The method is applicable to molecules and solids. © 2016 Wiley Periodicals, Inc.

The Pauli potential fulfills to a large extend the criteria of transferability and as such can be composed from its atomic fragments. This model provides a simple and fast procedure how to generate the Pauli potential of bound systems applicable in orbital-free density functional calculations of molecules and solids.

The substituent effects in aerogen bond interactions between ZO_{3} (Z = Kr, Xe) and different nitrogen bases are studied at the MP2/aug-cc-pVTZ level of theory. The nitrogen bases include the sp bases NCH, NCF, NCCl, NCBr, NCCN, NCOH, NCCH_{3} and the sp^{3} bases NH_{3}, NH_{2}F, NH_{2}Cl, NH_{2}Br, NH_{2}CN, NH_{2}OH, and NH_{2}CH_{3}. The nature of aerogen bonds in these complexes is analyzed by means of molecular electrostatic potential, electron localization function, quantum theory atoms in molecules, noncovalent interaction index, and natural bond orbital analyses. The interaction energy (*E*_{int}) ranges from −4.59 to −9.65 kcal/mol in the O_{3}Z···NCX complexes and from −5.30 to −13.57 kcal/mol in the O_{3}Z···NH_{2}X ones. The dominant charge-transfer interaction in these complexes occurs across the aerogen bond from the nitrogen lone-pair (n_{N}) of the Lewis base to the *σ**_{Z-O} antibonding orbital of the ZO_{3}. Besides, the formation of aerogen bond tends to decrease the ^{83}Kr or ^{131}Xe chemical shielding values in these complexes. © 2016 Wiley Periodicals, Inc.

A new sort of σ-hole interaction between covalently bonded group 18 atoms (known as rare gases or aerogens) was recently identified and named “aerogen bonding.” Aerogen bonds are comparable in strength to hydrogen bonds and other σ-hole-based interactions. First-principle modeling can provide an insight into the substituent effects in aerogen-bonded complexes. The formation of aerogen bond tends to decrease the ^{83}Kr or ^{131}Xe chemical shielding values in these complexes.

The regioselective polymerizations of isoprene and 3-methyl-pentadiene catalyzed by a cationic iron (II) complex bearing bipyridine ligand have been computationally studied. Having achieved an agreement between calculation and experiment, it is found that the open-shell unpaired 3d-electrons localize on Fe center rather than partially distribute on the redox-active bipyridine ligand. The steric effect plays a more important role in controlling the regioselectivity in comparison with electronic factors. The deformation energy is mainly contributed by monomer and Fe-alkyl moieties rather than the bipyridine ligands themselves, although noncyclopentadienyl ancillary ligands are often deformed in most insertion transition states for selective polymerization of olefin. © 2016 Wiley Periodicals, Inc.

DFT calculations indicate that steric effect plays an important role in the regioselectivity in the polymerizations of dienes catalyzed by a cationic bipyridine-ligated iron(II) complex. The catalytically active species is found to be at the open-shell quintuplet ground state with no spin distribution on the redox-active bipyridiene ligand.

We present accurate calculations of the non-autoionizing
and
doubly excited states of the H_{2} molecule using full configuration interaction with Hartree–Fock molecular orbitals and Heitler–London atomic orbitals. We consider the united atom configurations from He(2p2p) up to He(2p8g) and dissociation products from H_{2}(2p + 2p) up to H_{2}(2p + 6ℓ). Born–Oppenheimer calculations are carried out with extended and optimized Slater-type orbitals for a total of 40 states, 10 for each symmetry, covering the internuclear distances from the united atom to dissociation, which, for some states, is reached beyond 100 *a*_{0}. Occurrences of repulsive states cleanly interlaced between bound states with many vibrational levels are reported. Some of the potential minima are deep enough to accommodate many vibrational levels (up to 50). Noteworthy large equilibrium minima, like *R*_{eq} = 46.0 *a*_{0} in the
state dissociating as (2p + 6h) and with 18 vibrational levels. The occurrence of vertical excitations from the singly excited manifolds is analyzed. Several states present double minima generated by avoided crossings, some with a strong ionic character. © 2016 Wiley Periodicals, Inc.

Accurate computations of the potential energy curves for the H_{2} molecule are generally limited to the ground and singly excited states, because of computational challenges in computing potential energy curves for multiple-excited states. Accurate Full CI calculations, from the united atom to dissociation, for doubly excited states of the ^{1,3}
and ^{1,3}
manifolds are performed in this work, notably using Slater Type Orbitals.

The behavior of a driven symmetric triple well potential has been studied by developing an algorithm where the well-established Bohmian mechanics and time-dependent Fourier Grid Hamiltonian method are incorporated and the quantum theory of motion (QTM) phase space structures of the particle are constructed, both in “nonclassical” and “classical” limits. Comparison of QTM phase space structures with their classical analogues shows both similarity as well as dissimilarities. The temporal nature and the spatial symmetry of applied perturbation play crucial roles in having similar phase space structures. © 2016 Wiley Periodicals, Inc.

Triple well potential is a very good model for the study of the reaction dynamics of isomerization process among three species, as the three wells can represent the three species. Here, an algorithm for solving the “classical” Schrödinger equation using Bohmian mechanics and time-dependent Fourier Grid Hamiltonian method has been developed and applied to a driven symmetric triple well system.

We propose a new implementation of Ehrenfest molecular dynamics based on the configuration interaction theory using configuration state functions (CSF) as basis set originally proposed by Amano and Takatsuka (J. Chem. Phys. **2005**, 122, 084113). Our development consists of two independet new features. The first one deals with the problem on how to “identify” the molecular orbitals at a simulation time step in terms of those at the previous time step. By giving an exact expression of CSF Ehrenfest method, this problem naturaly vanishes. To actually perform this method, the concept of molecular orbital connection which allows the MOs to be noncanonical is necessary. The second feature of our method is aimed to reduce the computational cost. We propose an approximaion to effectively perform the time propagation of the electron wavefunction. Due to the analogy to the locally diabatic representation method, we name our method locally quasi-diabatic representation method. In the present work, these two new features were combined and employed to perform test computations. © 2016 Wiley Periodicals, Inc.

Ehrenfest dynamics is a commonly used mixed quantum classical technique. Here, a new computational scheme for *ab initio* Ehrenfest dynamics using configuration state function as basis is proposed. One of the main features of the method is exactly connecting molecular orbitals using analytic derivative of orbital coefficients of noncanonical orbitals. In the present method, there is no switch of orbital character as in canonical orbitals.

The difference between density functionals defined by energy criterion and density functionals defined by density criterion is studied for the exchange functional. It is shown that Slater potentials are exact exchange potentials in the sense that they yield the Hartree–Fock electron density if all operators are given by local expressions. © 2016 Wiley Periodicals, Inc.

Whereas the conventional functional design is based on an energy minimization procedure of a given energy expression, density functionals defined by density criterion are the expressions for the minimum of such a hypothetical minimization procedure. Consequently, the electron density and the energy are evaluated directly from the corresponding functional. It is shown that Slater potentials are exact local exchange potentials in case that the kinetic energy is also given by a local expression.

A density functional theory (DFT) approach was used to predict the thermodynamic energy barriers of the oxygen evolution reaction (OER) for three functionalized Metal-organic Frameworks (MOFs). A UiO-66(Zr) MOF design was selected for this study that incorporates three linker designs, a 1,4-benzenedicarboxylate (BDC), BDC functionalized with an amino group (BDC + NH_{2}), and BDC functionalized with nitro group (BDC + NO_{2}). The study found several key differences between homogeneous planar catalyst thermodynamics and MOF-based thermodynamics, the most significant being the non-unique or heterogeneity of reaction sites. Additionally, the functionalization of the MOF was found to significantly influence the hydroperoxyl binding energy, which proves to be the largest hurdle for both oxide and MOF-based catalyst. Both of these findings provide evidence that many of the limitations precluding planar homogeneous catalysts can be surpassed with a MOF-based catalyst. The BDC + NH_{2} proved to be the best performing catalyst with a predicted over-potential for spontaneous OER evolution to be 3.03eV. © 2016 Wiley Periodicals, Inc.

Metal-organic frameworks (MOFs) embody several tailorable material attributes that lend themselves well to sustainable water-splitting through photocatalysis. This study theoretically investigates the oxygen evolution reaction (OER) within a functionalized MOF pore. Findings include high heterogeneous reaction site affinity that surpassing physical limitation of planar catalyst. A 3.03 V OER over-potential was predicted for a UiO-66(Zr)-NH_{2} functionalized MOF.

DFT methods were utilized to study SCO complexes. [Fe(2btz)_{2}(NCX)_{2}] (2btz = 2,2′-bithiazoline, X = S (**1**) and Se (**2**)), [Fe(phen)_{2}(NCX)_{2}] (phen = 1,10-phenantroline, X = S (**3**) and Se (**4**)), and [Fe(bpy)_{2}(NCS)_{2}] (**5**) (bpy = 2,2′-bipyridine) compounds, which have experimentally shown SCO behavior, were calculated. B3LYP, B3LYP*, OPBE, and OLYP with 6-31G* and 6-311 + G** basis sets were employed to calculate the Δ*E*_{HS/LS} energy gap as a clue to find complexes with SCO behavior. It is found that calculated result by B3LYP* with c_{3} = 0.14 and OPBE methods and 6-31G* basis set are in agreement with experimentally observed SCO complexes. Then, newly designed Fe(N-N)_{2}(X)_{2} complexes, where N-N are bidentate nitrogen donor chelating ligands and X= SCN^{-}, SeCN^{-}, Cl^{-}, Br^{-}, I^{-},
were chosen to see their potential to be SCO compounds. Δ*E*_{HS/LS} for potential SCO complexes are estimated from 0.8 to 6.5 kcal/mol in B3LYP* and 0.6–5.7 kcal/mol in OPBE. These calculations suggest [Fe(bpy)_{2}(NCSe)_{2}], [Fe(5dmbpy)_{2}(NCS)_{2}], and [Fe(3-BrPhen)_{2}(NCSe)_{2}] compounds have the ability to show SCO behavior. © 2016 Wiley Periodicals, Inc.

To find good DFT method for reliable prediction of the correct splitting energy between low and high spin states for Iron complexes, B3LYP, B3LYP*, OPBE, and OLYP with 6-31G* and 6-311 + G** basis sets were employed to calculate the Δ*E*_{HS/LS} energy gap. B3LYP* with c_{3} = 0.14 and OPBE with 6-31G* basis set show a reasonable Δ*E*_{HS/LS} energy gap.

Consensus is still lacking on the best theoretical approach for the reliable prediction of the correct splitting energy between low and high spin states for Iron complexes. Popular Density Functional Theory approaches, B3LYP, B3LYP*, OPBE, and OLYP, and basis sets are put to the test to calculate the Δ*E*_{HS/LS} energy gap. B3LYP* with c_{3} = 0.14 and OPBE with 6-31G* basis set show the best agreement with experimental data.

In the present work, the applicability of some of the recently proposed and modern double-hybrid (DH) models and other density functional theory (DFT) approximations has been analyzed for a difficult test, the order of stability in low-energy isomers of water nanoclusters. In particular, we aim to systematically investigate for these functionals the role played by several factors such as dispersion correction, integrand functions upon which the DHs are based, and different spin scaling for the perturbative term in DH calculations of the relative energies for various isomers of water nanoclusters (H_{2}O)_{20}. From the obtained results, the superior performance of DHs with respect to the functionals from previous rungs is confirmed. It is shown that the dispersion corrected DHs perform better than noncorrected counterparts. Plus, the DH models based on cubic integrand (CI) and quadratic integrand (QI) functions are nearly equivalent in performance. We also find that using only contributions of electron pairs with opposite spin for the perturbative correlation part through scaled opposite spin scheme does not represent a significant improvement on accuracy of the results. Putting all the results together, the dispersion corrected parameterized DHs and parameter-free DH models involving CI and QI functions outperform other approximations for relative energies of water 20-mers. Altogether, predicting the correct order of the stability in water nanoclusters may be considered as another Achilles' heel in DFT calculations, although more analyses in this context are still needed. © 2016 Wiley Periodicals, Inc.

In this work, the applicability and accountability of a few modern double-hybrid models have been analyzed in detail for predicting the order of stabilities in low-energy isomers of water nanoclusters.

The interactions between temozolomide and chloroquine were examined via Dispersion-Corrected Density Functional Theory and MP2 methods. Chloroquine was considered in both its lowest energy structure and in a local minimum where its aromatic system and secondary amine group are free to interact directly with temozolomide. The accessibility of these two components to intermolecular interaction makes the lowest energy dimer of this local monomer minimum competitive in total energy with that involving chloroquine's most stable monomer geometry. In either case, the most stable heterodimer places the aromatic ring systems of the two molecules parallel and directly above one another in a stacked geometry. Most of the local minima are also characterized by a stacked geometry as well. Comparison between B3LYP and B3LYP-D binding energies confirms dispersion is a primary factor in stabilizing these structures. © 2016 Wiley Periodicals, Inc.

Temozolomide and chloroquine each contain an aromatic system conjoined with appending groups capable of forming strong H-bonds. The most important factor in the structure of heterodimers is the dispersion force between the two stacked aromatic systems. The strong intermolecular H-bonds formed by a secondary minimum of the chloroquine monomer with temozolomide can favor this heterodimer over one including the global minimum of chloroquine.

We have compared the performances of the one-parameter and linearly scaled one-parameter double-hybrid density functionals (1DH-DFs and LS1DH-DFs) for noncovalent interactions. The only one parameter related to the Hartree–Fock (HF) exchange for each of the tested 1DH-DFs and LS1DH-DFs has been fitted with the well-designed S66 database. The obtained DHDFs are dubbed as 1DH-PBE-NC, LS1DH-PBE-NC, 1DH-TPSS-NC, LS1DH-TPSS-NC, 1DH-PWB95-NC, and LS1DH-PWB95-NC, where “NC” denotes noncovalent interactions. With a specific combination of exchange and correlation functionals, the dependent parameters related to the nonlocal second-order perturbative energies are nearly identical for the 1DH and LS1DH models. According to our benchmark computations against the S66, S22B, NCCE31, ADIM6, and L7 databases, we suggest that the 1DH-PWB95-NC and LS1DH-PWB95-NC functionals are much more suitable for evaluating noncovalent interaction energies. Unlike the versatile DHDFs with dispersion corrections for general purpose, our optimized 1DH-DFs and LS1DH-DFs only aim at noncovalent interactions. © 2016 Wiley Periodicals, Inc.

As fifth rung approaches in density functional theory, double-hybrid density functionals are seen as efficient methods for electronic structure computations. These functionals are potentially promising for the treatment of non-covalent interactions because they contain nonlocal second-order perturbative energy terms, although correction terms are still sometimes needed. A benchmark study of one-parameter and linearly scaled one-parameter double-hybrid density functionals suggests that 1DH-PWB95-NC and LS1DH-PWB95-NC are the more suitable of these approaches for studying non-covalent interactions.

Recently, the quantum harmonic oscillator model has been combined with maximally localized Wannier functions to account for long-range dispersion interactions in density functional theory calculations (Silvestrelli, J. Chem. Phys. 2013, 139, 054106). Here, we present a new, improved set of values for the three parameters involved in this scheme. To test the new parameter set we have computed the potential energy curves for various systems, including an isolated Ar2 dimer, two N2 dimers interacting within different configurations, and a water molecule physisorbed on pristine graphene. While the original set of parameters generally overestimates the interaction energies and underestimates the equilibrium distances, the new parameterization substantially improves the agreement with experimental and theoretical reference values. © 2016 Wiley Periodicals, Inc.

A new parametrization for the quantum harmonic oscillator model to compute corrections due to the van der Waals interactions in density functional theory is proposed in this work. It is demonstrated that the improved parametrization substantially improves the agreement with experimental and theoretical reference values. Due to the fact that the present scheme can be seamlessly integrated into existing electronic structure codes, this development open the door to routinely compute the van der Waals interactions in the framework of density functional theory calculations.

Signal processing techniques have been developed that use different strategies to bypass the Nyquist sampling theorem in order to recover more information than a traditional discrete Fourier transform. Here we examine three such methods: filter diagonalization, compressed sensing, and super-resolution. We apply them to a broad range of signal forms commonly found in science and engineering in order to discover when and how each method can be used most profitably. We find that filter diagonalization provides the best results for Lorentzian signals, while compressed sensing and super-resolution perform better for arbitrary signals. © 2016 Wiley Periodicals, Inc.

Three methods for reconstructing a signal, e.g. in NMR, that beat the Nyquist limit in presence of prior information are discussed in terms of their successes, failures and characteristics. Compress sensing, super-resolution, and filter diagonalization are modern signal processing algorithms, but, despite their potential, they have not been yet widely adopted in chemistry.

We provide quantum chemical insights into curcumin's prevention of Alzheimer' disease through curcumin's scavenging of neurotoxic Cu(II), Zn(II), and Pd(II) transition metal ions that catalyze polymerization of amyloid-β and promote misfolding of amyloid into neurotoxic conformations. We have employed high level quantum chemical computations to study the chelate complexes of curcumin with Cu(II), Zn(II), and Pd(II). Quantum chemically derived structures, IR spectra, and UV-visible spectra of these complexes corroborate with the observed spectra, confirming that the primary site of chelation is the β-diketone bridge through the loss of an enolic proton of curcumin. We have also obtained the various structural parameters such as the Mulliken charges on various centers, highest occupied, lowest unoccupied molecular orbitals—all of which confirm that curcumin forms chelate complexes and thus acts as a scavenger of these neurotoxic metal ions preventing Alzheimer's disease. We find that the open-d-shell Cu(II) and Pd(II) form nearly square planar complexes while the closed-d-shell Zn(II) forms a tetrahedral complex with curcumin. © 2016 Wiley Periodicals, Inc.

Quantum chemical insights into Alzheimer's disease is presented. It is shown that curcumin scavenges neurotoxic Cu(II), Zn(II), and Pd(II) ions that catalyze polymerization and misfolding of amyloid-β protein through chelation as a mechanism for the prevention of Alzheimer's disease.

The computation of high-harmonic generation spectra by means of Gaussian basis sets in approaches propagating the time-dependent Schrödinger equation was explored. The efficiency of Gaussian functions specifically designed for the description of the continuum proposed by Kaufmann *et al*. (J Phys B 1989, 22, 2223) was investigated. The range of applicability of this approach was assessed by studying the hydrogen atom, that is, the simplest atom for which “exact” calculations on a grid could be performed. The effect of increasing the basis set cardinal number, the number of diffuse basis functions, and the number of Gaussian pseudo-continuum basis functions for various laser parameters was notably studied. The results showed that the latter significantly improved the description of the low-lying continuum states, and provided a satisfactory agreement with grid calculations for laser wavelengths *λ*_{0} = 800 and 1064 nm. The Kaufmann continuum functions, therefore, appeared as a promising way of constructing Gaussian basis sets for studying molecular electron dynamics in strong laser fields using time-dependent quantum-chemistry approaches. © 2016 Wiley Periodicals, Inc.

High-harmonic generation (HHG) is a highly nonlinear phenomenon which provides coherent XUV and soft X-ray radiation with attosecond (10^{−18} s) duration. HHG is also a powerful tool for studying atomic and molecular structures, combining a short temporal resolution with a high spatial resolution. HHG is characterized by electron excursion in the continuum. Electron dynamics is studied by means of the time-dependent Schrödinger equation using optimal Gaussian functions for the representation of the continuum states.

A concept for the interactions between π-systems is necessary to understand a number of phenomena in modern material sciences such as supramolecular properties and self-assembly. In the present article, we investigate the intermolecular interaction energies between organic semiconductors with extended π-systems using SAPT (symmetry-adapted perturbation theory), LMO-EDA (localized molecular orbital energy decomposition analysis), DFT-D (density functional theory including dispersion corrections), and force-field approaches. Both apolar organic molecules such as acenes and highly polarized π-systems of merocyanines and squaraines were used to probe the influence of electrostatics on the shape of the potential energy surfaces (PES) governing the geometric structures of aggregates. Our results reveal that the shapes of the PESs result from variations in the short-range, highly specific repulsion forces even for highly polar molecules. Using distributed quadrupoles, we show that it is nevertheless possible to mimic the intermolecular potentials with electrostatics. This is also possible with van-der-Waals potentials and a simple overlap-based force-field ansatz based on the overlap between p-orbitals. © 2016 Wiley Periodicals, Inc.

Interactions between π-systems are of major importance for a number of phenomena, such as supramolecular properties of organic semiconductors and molecular self-assembly in modern material sciences. Employing high-level SAPT, LMOEDA, and DFT-D calculations, this work demonstrates that the repulsion energy between monomers gives rise to characteristic features of the intermolecular potential energy surfaces. Electrostatic, van der Waals interactions, and overlap-based approaches can be used to mimic features of the intermolecular potential.

The nature of E···E' bonding in homonuclear (E = E') and heteronuclear (E ≠ E') [Nap(EPh)(E'Ph)]^{•+} (E, E' = O, S, Se, and Te) radical cations has been investigated by quantum chemistry and the topological analysis of electron density. The calculation results show that the E···E' bonding in the title compounds occurs through attractive interactions; O···E' (E'=O, S, Se, and Te) bonding are electrostatic interactions, and the others have a partial covalent character. The nature of E···E' bonding varies periodically, with the changes of E' atoms going from the lighter to the heavier (O, S, Se, and Te). Both in homonuclear and heteronuclear [Nap(EPh)(E'Ph)]^{•+}, for the same E atom, a heavier E' atom means stronger E···E/E' bonding, a more covalent character of the E···E' bond, and more spin electron density transfers from benzene rings to the E···E' group. © 2016 Wiley Periodicals, Inc.

Some sulfur radical cations contain a two center-three-electron (2c-3e) σ-bond, also known as ‘hemibond’. These 2c-3e σ-bonded radicals are characterized by a relatively weak bond between the two atoms. The geometry of model radicals and the nature of E…E' bonding in them is investigated *in silico*. The geometry and E…E' bonding varies periodically with the changes of E' atoms going from the lighter to the heavier (O, S, Se, and Te).

New medium size Gaussian-type basis set R-ORP for evaluation of static and dynamic electric properties in molecular systems is presented. It is obtained in a close resemblance to the original ORP basis set, from the source basis set through addition of two first-order polarization functions whose exponent values are optimized with respect to the finite field restricted open-shell Hartree–Fock (ROHF) atomic polarizabilities. As the source set the VTZ basis set of Ahlrichs and coworkers, augmented with additional diffuse functions and contracted to the form [6s/3s] for hydrogen and [11s7p/4s3p] for carbon through fluorine, is chosen. The resulting basis set is of the form [6s2p/3s2p] for hydrogen and [11s7p2d/4s3p2d] for other atoms. Presented basis set is next tested in the CCSD static and dynamic molecular polarizability and hyperpolarizability calculations for a set of ten and four test molecules, respectively, for which very accurate reference data exist. Additionally, the recently developed ORP basis set is employed in the calculations to examine the limits of its applicability. Results are compared to the literature data obtained in both, large and diffuse, as well as reduced-size basis sets. In the case of polarizability calculations, the aug-pc-1 and R-ORP are the optimal choices among the investigated smaller basis sets, with the overall performance of the aug-pc-1 set being better. Among the larger sets, the ORP performs better in the case of average polarizability, while the RMSE values for polarizability anisotropy are practically identical for d-aug-cc-pVDZ and ORP sets. Finally, the R-ORP and ORP basis sets compete other small bases in the evaluation of the first hyperpolarizability in investigated systems. © 2016 Wiley Periodicals, Inc.

New polarized R-ORP basis set for evaluation of static and dynamic electric properties in molecular systems is developed and tested in calculation of polarizability and first hyperpolarizability of test systems together with the recently developed ORP basis set. Both sets are valuable alternative to traditional basis sets in the evaluation of first hyperpolarizability.

Working from the arrangements of both row and group numbers developed within Mendeleev's periodic table of elements, periodic trends can be shown to exist in many constants of triatomic molecules: an extension of the Periodic Law for atoms to the realm of molecules. Trends are identified for vibrational frequencies, bond lengths, and to a lesser extent interior angles. This work includes empirical sources for such data, supplemented with calculations using diatomic analogs where possible. Otherwise, computation is used for all possible configurations of row two and row three main-group elements to both corroborate and extend empirical results. Organization of this data into a detailed, highly symmetric, multidimensional coordinate system allows for robust graphical and statistical analysis of all constants and associated trends, which in turn permits rapid identification of suspect data to be rechecked. All collected empirical and computational data, along with several interactive visualizations highlighting these results, is available online. © 2016 Wiley Periodicals, Inc.

This work shows there exists periodic behavior across all triatomic molecules in consideration of their vibrational frequencies, and to a lesser extent their bond lengths and angles, as compiled from both experimental studies and computational simulations. A Mendeleevian numbering scheme of group/row number coordinates to make a highly-symmetric, 13-dimensional form is used. These results restate the Periodic Law in a molecular rather than elemental sense, a satisfying but not necessarily expected result, given quantum mechanical complexity.

We study a wavepacket tunneling in one-dimensional periodically driven double-well system using entangled trajectory molecular dynamics method. The tunneling dynamics dependents on the amplitude and frequency of the driven force are present. Both resonant and nonresonant tunneling process are enhanced by the driven force when the system is chaotic under classical dynamics. We give entangled trajectory in phase space compared to corresponding classical trajectory with same initial state to visually show quantum tunneling process. The average values of quantum tunneling probability after long time evolution have been shown in the parameter spaces, the effect of resonance and chaos on the tunneling dynamics are present. The relation between chaos and the uncertainly product is discussed in the end. © 2016 Wiley Periodicals, Inc.

Wavepacket tunneling in one-dimensional, periodically driven doublewell system, can be efficiently studied using entangled trajectory molecular dynamics method. Tunneling dynamics depends on the amplitude and frequency of the driven force, when the system is chaotic under classical dynamics. Chaos is found to enhance both resonant and non-resonant tunneling processes. The increase of the perturbation strength enhances the increment of the quantum fluctuation in the case of same frequency.

Quantum mechanical exchange effects in purely organic *N*,*N*′-dioxy-2,6-diazaadamantane biradical derivatives with promesogenic substituents have been studied. To determine intermolecular exchange energies, packing conditions of the radical core units in layered liquid crystalline phases are simulated using the Gaussian 09 program. The broken symmetry approach gives J ≈ 7 cm^{−1} for intramolecular ferromagnetic exchange interactions between nitroxyl radical centers in one molecule. Both ferromagnetic and antiferromagnetic intermolecular interactions are possible in this kind of systems according to the obtained calculation results. Depending on the mutual positioning and orientation of molecules, the intermolecular antiferromagnetic exchange constant can reach a value of −50 cm^{−1}, and the intermolecular ferromagnetic constant a value of 10 cm^{−1}. The simultaneous presence of intramolecular and intermolecular exchange between spin-carrying centers in this kind of supramolecularly ordered multispin systems is favorable for the formation of magnetically interacting chains and two-dimensional networks. © 2016 Wiley Periodicals, Inc.

Organic ferromagnetic materials, based on organic compounds containing stable free radicals, have been theoretically suggested for subsequent synthesis. The effects of liquid crystalline supramolecular organization and, possibly, ferroelectric ordering on the magnetic properties of organic radicals are currently subjects of considerable interest. Liquid crystalline order in *N*,*N*′-dioxy-2,6-diazaadamantane biradicals can lead to the both ferromagnetically and antiferromagnetically coupled chains and networks, as shown by quantum-chemical calculations.

Solid-state NMR spectroscopy and computational approaches such as Molecular Dynamics (MD) simulations and Density Functional Theory have proven to be very useful and versatile techniques for studying the structure and the dynamics of noncrystalline materials if a direct comparison between experiment and theory is established. In this review, the basic concepts in first-principle modeling of solid-state NMR spectra of oxide glasses are presented. There are three theoretical ingredients in the computational recipe. First, classical or *ab initio* molecular dynamics simulations are employed to generate the structural models of the glasses of interest. Second, periodic Density Functional Theory calculations coupled with the gauge including projector augmented-wave (GIPAW) algorithm form the basis for the *ab initio* calculations of NMR parameters (chemical shielding and quadrupolar parameters). Finally, Spin-effective Hamiltonian are employed to simulate the solid-state NMR spectra directly comparable with the experimental counterparts. As an example of this methodology, the investigation of the local and medium range structure of Na-Ca silicate and aluminosilicate glasses that are usually employed as simplified models for basaltic, andesitic and rhyolitic magmas will be reported. We will show how the direct comparison of the theoretical NMR spectra of MD derived structural models with the experimental counterparts allows gaining new insights into the atomistic structure of very complex oxide glasses. © 2016 Wiley Periodicals, Inc.

Molecular dynamics simulations coupled with DFT-GIPAW NMR calculations and spin-effective Hamiltonians provide a clear view of the local and medium range structure of multicomponent alumina silicate glasses.

On page 1016 Sudip Pan, Ranajit Saha, Anand Kumar, Ashutosh Gupta, Gabriel Merino, and Pratim K. Chattaraj computationally assess the noble gas binding ability of noble metal (Cu, Ag, Au) oxides. The stability of noble gas bound metal oxides is further compared with the experimentally detected noble gas bound noble metal halides. The nature of bonding is investigated via natural bond orbital, electron density, and energy decomposition analyses. The bond in between noble metal and noble gas may be considered as partly covalent and partly electrostatic in nature. (DOI: 10.1002/qua.25121)

We have studied how ReaxFF and Behler–Parrinello neural network (BPNN) atomistic potentials should be trained to be accurate and tractable across multiple structural regimes of Au as a representative example of a single-component material. We trained these potentials using subsets of 9,972 Kohn-Sham density functional theory calculations and then validated their predictions against the untrained data. Our best ReaxFF potential was trained from 848 data points and could reliably predict surface and bulk data; however, it was substantially less accurate for molecular clusters of 126 atoms or fewer. Training the ReaxFF potential to more data also resulted in overfitting and lower accuracy. In contrast, BPNN could be fit to 9,734 calculations, and this potential performed comparably or better than ReaxFF across all regimes. However, the BPNN potential in this implementation brings significantly higher computational cost. © 2016 Wiley Periodicals, Inc.

ReaxFF, and the Behler-Parrinello neural network (BPNN) atomistic potential were trained from density functional theory calculations to be accurate and tractable across multiple structural regimes of Au. It was found that the BPNN potential can be trained from much larger training sets to perform comparably or significantly better than ReaxFF across all regimes. However, in the implementation used in this work, the BPNN potential also brings significantly higher computational cost.

This DFT study examined the interaction of a sulfated zirconia (SZ) slab model system (heterogeneous catalyst) and triacetin (a precursor in biodiesel production) using explicit methanol solvent molecules. Full geometry optimizations of the systems were performed at the B3LYP level of theory. Gibbs free energies provide insight into the spontaneity of the reactions along a three-step reaction mechanism for the transesterification of triacetin. Charge decomposition analysis revealed electronic charge transfer between the metallic oxide and the organic moieties involved in the reaction mechanism. Fukui indices indicate the likely locations on the SZ surface where catalysis may occur. The quadratic synchronous transit scheme was used to locate transition structures for each step of the transesterification process. The results are in agreement with the strongly acidic catalytic character of zirconium observed experimentally in the production of biodiesel. © 2016 Wiley Periodicals, Inc.

Biodiesel is seen as an environmentally sustainable alternative to the use of fossil fuels. The reaction mechanism and charge transfer of triacetin, a precursor in biodiesel production, on sulfated zirconia as a heterogeneous catalyst can be analyzed using computational chemistry techniques. The study provides an insight on the catalytic properties of sulfated zirconia and its role on the transesterification of triacetin.

We have performed the first-principles calculations on the structural, electronic, and magnetic properties of 3d transition-metal™ (Cr, Mn, Fe, Co, and Ni) atoms doped 2D GaN nanosheet. The results show that 3d TM atom substituting one Ga leads to a structural reconstruction around the 3d TM impurity compared to the pristine GaN nanosheet. The doping of TM atom can induce magnetic moments, which are mainly located on the 3d TM atom and its nearest-neighbor N atoms. It is found that Mn- and Ni-doped GaN nanosheet with 100% spin polarization characters seem to be good candidates for spintronic applications. When two Ga atoms are substituted by two TM dopants, the ferromagnetic (FM) ordering becomes energetically more favorable for Cr-, Mn-, and Ni-doped GaN nanosheet with different distances of two TM atoms. On the contrary, the antiferromagnetic (AFM) ordering is energetically more favorable for Fe-doped GaN nanosheet. In addition, our GGA + *U* calculations show the similar results with GGA calculations. © 2016 Wiley Periodicals, Inc.

Although 2D gallium nitride (GaN) nanosheets are non-magnetic, their doping with 3d transition metal atoms (Cr, Mn, Fe, Co, and Ni) can induce magnetization. The magnetic properties of 2D GaN-based diluted magnetic semiconductors mainly originate from the 3d electrons of the transition atoms. Theoretical calculations suggest that the 3d metal-doped GaN nanosheet maybe be used successfully as spintronic and magnetic data storage materials.

A DFT study was carried out on the ground state structures of ternary Cu_{l}Ag_{m}Au_{n} (*l* + *m* + *n* = 6) clusters, with the aim of investigating changes of thermal and kinetic stabilities as an effect of composition, as well as the composition dependence of the electrostatic potential, of stable planar structures. DFT optimizations were performed using the PBE functional and the SDD basis set. All the optimized structures adopt planar geometries with bent triangular structures. Calculated binding energy values are in the range 1.5–1.9 eV/atom, which shows their thermal stability. The predicted HOMO-LUMO energy gap values are in the semiconductor region, providing a qualitative indication of a moderate kinetic stability. NBO analyses indicate the existence of two mechanisms promoting planar structural stability, one due to bonding-antibonding orbital interaction, and the other one due to the well-known spd hybridization. Wiberg indices were obtained showing interatomic bonding. Electrostatic potential calculations show the existence of nucleophilic attack regions preferentially around silver and copper atoms located at the vertices while electrophilic attack regions are found in the vicinity of gold atoms over the cluster plane. Apparently, charge transfer occurs toward gold from silver and copper atoms when the concentration is favorable in the proximity of gold atoms. In particular, if the small ternary clusters discussed here contain only one gold atom, then a high electron density is observed at the site of this gold atom. © 2016 Wiley Periodicals, Inc.

Density Functional Theory calculations elucidate the structure of 6-atom ternary noble metal clusters. As similarly seen in the case of small bimetallic clusters, planar structures are found, with an energy gap consistent with semiconductor nanoparticles. The planarity of the ground state structures thus obtained is analyzed through the natural bond orbital scheme, and the electrostatic potential at different atomic sites is obtained to be employed as a reactivity descriptor.

An *in silico* study is performed on the structure and the stability of noble gas (Ng) bound MO complexes (M = Cu, Ag, Au). To understand the stability of these Ng bound complexes, dissociation energies, dissociation enthalpy, and dissociation free energy change are computed. The stability of NgMO is also compared with that of the experimentally detected NgMX (X= F, Cl, Br). It is found that MO has lower Ng binding ability than that of MX. All the dissociation processes producing Ng and MO are endothermic in nature and for the Kr-Rn bound MO (M = Cu, Au), and Xe and Rn bound AgO cases, the corresponding dissociation processes are turned out to be endergonic in nature at standard state. The Wiberg bond indices of NgM bonds and NgM electron transfer gradually increase from Ar to Rn and for the same Ng they follow the order of NgAuO > NgCuO > NgAgO. Energy decomposition analysis shows that the NgM bonds in NgMO are partly covalent and partly electrostatic in nature. Electron density analysis further highlights the partial covalent character in NgM bonds. © 2016 Wiley Periodicals, Inc.

The nature of the interaction between noble metals and noble gasses has been at the center of a lively debate. The noble gas binding ability of noble metal (Cu, Ag, Au) oxides is explored by employing high-level *ab initio* methods. The stability of noble gas bound metal oxides are very comparable to that of experimentally detected noble gas bound noble metal halides.

The nature of the bonding interactions including the intramolecular SS interactions in tetrasulfur tetranitride, S_{4}N_{4} are probed by performing very large amplitude vibrations of all of the 18 normal modes of vibration. The QTAIM and stress tensor point properties are -then investigated and found to be highly dependent on the mode of vibration. A considerable degree of metallicity ξ(**r**_{b}) is found for the SS and SN bonding interactions. A unique bonding feature is found for a small amplitude vibration of the most anharmonic mode of this investigation, mode 2, where the SS bond critical point (BCP) transforms from a closed-shell SS BCP to a shared-shell SS BCP. We find 17 new unique QTAIM topologies for the molecular graphs corresponding to the 18 modes of vibration along with seven “missing” topologies that are mapped onto a spanning 2-D Quantum topology Phase Diagram (QTPD). In addition, eleven unique topologies existing on 3-D QTPDs are found due to the presence of non-nuclear attractors (NNAs). We use the stress tensor eigenvalues to explain the invariance of the numbers and types of QTAIM critical points. The applicability of both the stiffness *S* and stress tensor stiffness *S*_{σ} are also explored. Two new bond measures are introduced, a polarizability *P* and the stress tensor polarizability *P*_{σ} which are derived from the stiffness *S* and stress tensor stiffness *S*_{σ}, respectively. © 2016 Wiley Periodicals, Inc.

Tetrasulfur tetranitride, S_{4}N_{4} can form a large number of compounds that have been experimentally obtained, including the long chain polymeric sulfur nitride and a variety of small molecules produced from the polymer. The structural flexibility of the molecule is one of the most important factors affecting the reactivity of S_{4}N_{4.} The QTAIM and stress tensor point properties are found to be highly dependent on the mode of vibration of the molecules.

Many fermions Kramers pairs formalism is considered from the prospective of the sum of individual single fermion time-reversal operators. The obtained many fermions “pseudo Kramers pairs operator” ( ), as well as its square ( ), have formally the same structure as the many fermion spin operators and . Nevertheless, the shape of eigenfunctions with respect to and is different. Herein all Kramers adapted eigenfunctions of for cases of up to four unpaired fermions are compiled, and their properties with respect to further advocated. It will be shown that degeneracy of the multiplets recovers the proper behavior with respect to Pascal's triangle. A projection operator for obtaining the “high spin” Kramers adapted eigenfunctions is suggested. Noncommutation of with spin and angular momentum operators and degeneracy is discussed at last. © 2016 Wiley Periodicals, Inc.

Pseudo Kramers symmetry is introduced upon spin additivity. Eigenfunctions of pseudo Kramers operator squared are presented for cases with up to four unpaired fermions. Eigenvalues of the pseudo Kramers operator squared correlate directly with the number of open shells. The obtained pseudo Kramers symmetry functions have the degeneracy closely related to coefficients in Pascal's triangle.