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Single crystals of an organic charge-transfer compound, 4-nitrobenzyl isoquinolinium picrate, [4NO2BzIQl][PIC](1), were grown by slow evaporation technique at room temperature. Single crystal XRD and powder XRD studies conform the crystal structure and crystalline nature. In the title compound, the [4NO2BzIQl]+ cations and the [PIC]- anions stack into a columnar structure through π···π and C H···π interactions. The FT-IR and Raman spectra were recorded and analyzed with the aid of density functional theory calculations in order to make a suitable assignment of the observed bands. The simulated spectrum satisfactorily coincides with the experimental UV–visible spectrum. Thermal stability and the major gaseous products of decomposition at 293 °C were examined by TG-DTA-MS technique. The material shows three main emission peaks about 385, 467 and 538 nm upon excitation at 241 nm in solid state at room temperature. The excited state energy from theoretical UV–vis spectra, the total energy of intramolecular interactions and nonlinear optical properties were studied using DFT calculations.

Electrostatic drag in the intramolecular Schmidt reactions of azidopropylcyclohexanones is characterized using density functional theory (DFT) calculations and direct dynamics simulations. Despite resulting from enthalpically favorable interactions, electrostatic drag slows down N2 loss during formation of bridged lactam products, an effect with implications for controlling product selectivity.

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Au-catalyzed propargyl ester reactions have been investigated by a comprehensive density functional theory (DFT) study. Our calculations explain the experimental observed chemoselectivity of Au-catalyzed propargyl ester reactions very well by considering all possible pathways both in the absence and presence of 1,2,3-triazole (TA). The “X-factor” of TA is disclosed to have triple effects on this reaction. First of all, it can stabilize and prevent rapid decomposition of the Au catalyst. Secondly, the existence of TA promotes the nucleophilic attack and alters the chemoselectivity of this reaction. Moreover, TA acts as a “relay” to promote the proton transfer.

The hydrogen storage behavior of alkali and alkaline-earth metal (AM = Li, Na, K, Mg, Ca) atoms decorated C24 fullerene was investigated by using density functional theory (DFT) study. Our results indicate that the AM atoms prefer to adsorb atop the center of tetragon of C24 fullerene with the largest binding energy than other possible adsorption sites. Moreover, the hydrogen storage gravimetric density of 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations reaches up to 12.7 wt%, 10.1 wt% and 12 wt%, higher than the year 2020 target from the US department of energy (DOE). Also, the average adsorption energies of H2 molecules of the 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations are −0.198 eV/H2, −0.164 eV/H2 and −0.138 eV/H2, locate the desirable range under the physical adsorption at near ambient conditions. These findings will have important implications on designing new hydrogen storage materials in the future.

Phosphonates are efficient corrosion and scale inhibitors commonly used in industrial circulating water systems. However, conventional detection methods cannot accurately detect their concentration in some water bodies and sludge because of their low concentration. In this study, a ratiometric fluorescent probe was constructed based on quercetin (QC) and divalent zinc ion (Zn2+) to comparatively detect three typical phosphonates for the first time. Compared with the naked QC, Zn2+-quercetin complex (ZnQC) in the designed probe shows considerable differences in terms of luminescence properties and surface morphology. When the concentration of QC and Zn2+ were 10 mM and 50 μM, the detection limits for ATMP, HEDP, and DTPMPA were 0.223, 0.205 and 0.152 μM, respectively, which were lower than of the corresponding values obtained through the chromatography method and phosphomolybdenum blue spectrophotometry. Moreover, for the first time, the quantitative analysis of molecular surface, basin analysis, and atoms in molecules (AIM) analysis and non-covalent interaction analysis (NCI) in the Multiwfn program were employed to investigate the binding sites of QC with Zn2+. The electron excitation properties were further analyzed via theoretical calculations based on the dependent density functional theory (DFT) and time-dependent density functional theory (TDDFT). The detection mechanism can be ascribed to the static quenching considering the formation of non-fluorescent ground-state complexes. Additionally, the ratiometric probe demonstrated some features such as high sensitivity, selectivity, and a simpler operation which has been applied to detect practical water samples with satisfactory results.

We report growth, electronic structure and superconductivity of ultrathin epitaxial CoSi2 films on Si (111). At low coverages, preferred islands with 2, 5 and 6 monolayers height develop, which agrees well with the surface energy calculation. We observe clear quantum well states as a result of electronic confinement and their dispersion agrees well with density functional theory calculations, indicating weak correlation effect despite strong contributions from Co 3d electrons. Ex situ transport measurements show that superconductivity persists down to at least 10 monolayers, with reduced T c but largely enhanced upper critical field. Our study opens up the opportunity to study the interplay between quantum confinement, interfacial symmetry breaking and superconductivity in an epitaxial silicide film, which is technologically relevant in microelectronics.

Porous potassium-promoted iron oxide, with the potassium content of 8 wt% can produce dense hydrogen materials as a catalyst. In this letter, we use density functional theory (DFT) and the generalized gradient approximation (GGA) to study this catalyst. Rhombohedral α-Fe 2 O 3 is used to build a porous model. We randomly put potassium atoms in the clean porous structure and iron-vacant defective structure. The results show that potassium atoms eventually exist in the form of clusters in the two samples. To further study the effect of potassium, clean and two K-promoted models are filled with the same quantity of H 2 . We obtain that the existence of potassium clusters prevents hydrogen molecules to dissociate into atoms in non-defective porous iron oxide. Most of the hydrogen atoms still exist in the form of hydrogen molecules in three models. The structures of potassium clusters for 2 ≤ N ≤ 8 in the porous model are also discussed, in contrast to the isolated clusters.

A novel gold-catalyzed intermolecular ynamide amination-initiated aza-Nazarov cyclization has been developed, allowing the facile and efficient synthesis of various 2-aminopyrroles in moderate to good yields. Furthermore, a mechanistic rationale for this tandem sequence, especially for the observed high regioselectivity, is also well supported by DFT (density functional theory) computations. The high flexibility, broad substrate scope, and mild nature of this reaction render it a viable alternative for the construction of 2-aminopyrroles.

A novel gold-catalyzed tandem intermolecular ynamide amination/C–H functionalization has been developed. A variety of highly functionalized 2-aza-1,3-butadienes can be obtained readily by utilizing this strategy. In addition, α-imino gold carbene intermediates are proposed in this amination reaction and with support by DFT (density functional theory) calculations.

A novel gold-catalyzed intermolecular ynamide amination-initiated aza-Nazarov cyclization has been developed, allowing the facile and efficient synthesis of various 2-aminopyrroles in moderate to good yields. Furthermore, a mechanistic rationale for this tandem sequence, especially for the observed high regioselectivity, is also well supported by DFT (density functional theory) computations. The high flexibility, broad substrate scope, and mild nature of this reaction render it a viable alternative for the construction of 2-aminopyrroles.

Planar Möbius aromatic metallacycles show NIR absorption spectrum and the highest carbon coordination number for a metal atom., The coordinating atoms in polydentate chelates are primarily heteroatoms. We present the first examples of pentadentate chelates with all binding atoms of the chelating agent being carbon atoms, denoted as CCCCC chelates. Having up to five metal-carbon bonds in the equatorial plane has not been previously observed in transition metal chemistry. Density functional theory calculations showed that the planar metallacycle has extended Craig-Möbius aromaticity arising from 12-center–12-electron dπ-pπ π-conjugation. These planar chelates have broad absorption in the ultraviolet-visible–near-infrared region and, thus, notable photothermal performance upon irradiation by an 808-nm laser, indicating that these chelates have potential applications in photothermal therapy. The combination of facile synthesis, high stability, and broad absorption of these complexes could make the polydentate carbon chain a novel building block in coordination chemistry.

We have performed a systematic density functional study on the ground-state electronic structure and excited states of a representative D-σ-A dyad, i.e. EDT-TTF-Im-F4TCNQ π-radical, in vacuo and in different conventional solvents (toluene, THF, DMF and DMSO) by using some popular hybrid density functionals (B3LYP, M05, M05-2X, PBE0 and BMK). It has been shown that the M05 and B3LYP functionals perform the best in predicting the intramolecular charge-transfer (ICT) pertaining to both the ground state and excited states of the dyad. The amphoteric dyad is liable to solvent-promoted ICT from its EDT-TTF-Im donor (D) to F4TCNQ acceptor (A), adopting a charge-unseparated ground state D-A• in vacuo, a partially zwitterionic ground state [D-A]• in nonpolar toluene solvent, and a fully zwitterionic ground state D•+-A- in such polar solvents as THF, DMF and DMSO. Owing to its solvent-dependent chameleon ground state, excited states of the dyad in solvents also exhibit remarkable dependence on solvent polarity, as revealed by TDDFT calculations. Furthermore, cluster model calculations revealed that intermolecular charge-transfer readily occurs between the dyads, accounting for the observed zwitterionic charge state in solid state and solid-state semiconductivity.

The low-lying states of an organic donor-σ-acceptor dyad, i.e. tetrathiafulvalene-σ-tetracyano-p-quinodimethane (TTF-σ-TCNQ), in gas phase and in various solvents have been investigated by means of hybrid DFT calculations in combination with the conductor-like polarizable continuum model to describe solvent effects. It has been shown that the dyad, though preferring a closed-shell singlet ground state with an eclipsed conformation in gas phase, adopts the charge-separated zwitterionic states with an extended conformation (TTF+-σ-TCNQ-), i.e. open-shell singlet biradical ground state immediately followed by triplet biradical state, in polar solvent ( CH3CN and CH2Cl2 ) as a result of the intramolecular electron transfer (ET) stimulated by solvent polarization. The degree of such intramolecular ET is so strongly dependent on the polarity (dielectric constant) of solvent that the zwitterionic biradical states become more stable with respect to the closed-shell singlet state with increasing polarity of the solvent. As such, the dyad should show a higher ratio of biradicals in more polar solvent and/or at higher temperature and, hence, is chameleonic in nature.

In this article, density functional theory has been utilized to study on the correlation between impact sensitivities h 50% and the bond dissociation energies (BDEs) of nine triazole energetic explosives. By employing B3LYP and B3P86 method with the 6-311G** basis set, all the molecules have been fully optimized. The BDEs for removal of the NO2 group in these compounds have also been calculated at the same level. Computed results show that BDEs calculated by B3LYP method are all less than those by B3P86 method. The relationship between the impact sensitivities and the weakest C–NO2 bond dissociation energy (BDE) values have been investigated. The results indicate a good linear correlation between the impact sensitivity h 50% and the ratio (BDE/E) of the weakest BDE to the total energy E.

Gauge-independent atomic orbital (GIAO) method at Hartree-Fock (HF) and density functional theory (DFT) levels, respectively, was employed to calculate 19F NMR chemical shieldings of solid state alkaline-earth-metal fluorides MF2 (M = Mg, Ca, Sr, Ba). The results show that, although the calculated 19F chemical shieldings tend to be larger than the experimental values, they have a fairly good linear relationship with the observed ones. The calculated results based on different combinations of basis sets show that the B3LYP (a hybrid of DFT with HF) predictions are greatly superior to the HF predictions. When a basis set of metal atom with effective core potential (ECP) has well representation of valence wavefunction, especially wavefunction of d component, and proper definition of core electron number, it can be applied to obtain 19F chemical shielding which is close to that of all-electron calculation. The variation of 19F chemical shielding of alkaline-earth-metal fluorides correlates well with the lattice factor A/R2.

Recently, a series of graphene-like binary monolayers (g-SiC x ), where Si partly substitutes the C positions in graphene, have been obtained by tailoring the band gaps of graphene and silicene that have made them a promising material for application in opto-electronic devices. Subsequently, evaluating the mechanical properties of g-SiC x has assumed great importance for engineering applications. In this study, we quantified the in-plane mechanical properties of g-SiC x (x = 7, 5, 3, 2 and 1) monolayers (also including graphene and silicene) based on density function theory. It was found that the mechanical parameters of g-SiC x , such as the ideal strength, Young's modulus, shear modulus, Poisson's ratio, as well as fracture toughness, are overall related to the ratio of Si-C to C-C bonds, which varies with Si concentration. However, for g-SiC7 and g-SiC3, the mechanical properties seem to depend on the structure because in g-SiC7, the C-C bond strength is severely weakened by abnormal stretching, and in g-SiC3, conjugation structure is formed. The microscopic failure of g-SiC x exhibits diverse styles depending on the more complex structural deformation modes introduced by Si substitution. We elaborated the structure-properties relationship of g-SiC x during the failure process, and in particular, found that the structural transformation of g-SiC3 and g-SiC is due to the singular symmetry of their structure. Due to the homogeneous phase, all the g-SiC x investigated in this study preserve rigorous isotropic Young's moduli and Poisson's ratios. With versatile mechanical performances, the family of g-SiC x may facilitate the design of advanced two-dimensional materials to meet the needs for practical mechanical engineering applications. The results offer a fundamental understanding of the mechanical behaviors of g-SiC x monolayers.

This paper calculates the elastic, thermodynamic and electronic properties of pyrite (Pa) RuO2 by the plane-wave pseudopotential density functional theory (DFT) method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle–ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.

We investigate the structural and elastic properties of γTiAl under high pressures using the norm-conserving pseudopotentials within the local density approximation (LDA) in the frame of density functional theory. The calculated pressure dependence of the elastic constants is in excellent agreement with the experimental results. The elastic constants and anisotropy as a function of applied pressure are presented. Through the quasi-harmonic Debye model, we also investigate the thermodynamic properties of γTiAl.

Solid-state NMR experiments and quantum chemical Density Functional Theory (DFT) calculations were employed to investigate the formation, location, and photocatalytic reactivity of methoxy species on anhydrous 12-H3PW12O40. Two different types of methoxy species were identified on the methanol-adsorbed 12-H3PW12O40 catalyst. Rotational Echo DOuble Resonance (REDOR) NMR experiments combined with quantum chemical DFT calculations demonstrated that the two corresponding methyl groups reside on the O-c and O-d atoms of the Keggin anion, forming the surface OcCH3 and OdCH3 species. Photocatalytic experiments further indicated that the two methoxy species are both photochemically reactive species with the OdCH3 species being much more reactive, and the methoxy species are preferentially mineralized to the final product CO2 directly.

The electronic ground states of [n]cyclacenes, as well as short-zigzag nanotubes, computed at unrestricted broken spin-symmetry density functional theory (UBS-DFT), were found to be open-shell singlets, rather than triplets. Computations for [6]cyclacene at complete active space self-consistent field (CASSCF) and multireference perturbation theory (MRMP2) levels support this conclusion. Along with strain, the radical character of the open-shell singlet with antiferromagnetically coupled electron spins may contribute to the difficulties in synthesizing [n]cyclacenes.

The reaction of Cr O 2 + ( 2 A 1 / 4 A ″ ) + C 2 H 4 to yield CrO + ( 2 Σ g / 4 Σ g ) + C 2 H 4 O, which is the continued research on the gas-phase reaction of Cr O 2 + with C 2 H 4 , has been investigated using density functional theory (DFT) at the UB3LYP/6-311++G(3df, 3pd)//6-311G(2d, p) level. There is different reaction mechanism between the doublet and quartet PESs. A crossing seam between CP1 and CP2 is located. In addition, the crossing caused by SOC is efficient. The conclusion has been proved by the frontier molecular orbital interaction analyses about CP1 and CP2.

In this paper the equilibrium structure of HCO has been optimized by using density functional theory (DFT)/ B3P86 method and CC-PVTZ basis. It has a bent (Cs, X2A') ground state structure with an angle of 124.4095 °. The vibronic frequencies and force constants have also been calculated. Based on the principles of atomic and molecular reaction statics, the possible electronic states and reasonable dissociation limits for the ground state of HCO molecule have been determined. The analytic potential energy function of HCO (X2 A') molecule has been derived by using the many-body expansion theory. The contour lines are constructed, which show the static properties of HCO (X2A'), such as the equilibrium structure, the lowest energies, etc. The potential energy surface of HCO (X2A') is reasonable and very satisfactory.

Because secondary explosives are stable molecules with large energy barriers to chemical reaction, in shock or impact initiation, a sizable amount of phonon energy must be converted to the molecular internal higher vibrations by multiphonon up pumping. To investigate the relationship between impact sensitivities and energy transfer rate, the number of doorway modes of explosives is estimated by a simple theory in which the rate is proportional to the number of normal mode vibrations. We evaluated frequencies of normal mode vibrations of 2,4,6-trinitro- m -cresol (C 7 H 5 N 3 O 7 ), picric acid, TNB, TNAP, TNT, TNA, TBN, DATB, and TATB by means of density functional theory (DFT) at the b3p86/6-31g (d,p) level. The number of doorway modes in the regions of 200–700 cm −1 was evaluated by the direct counting method. It is found that the number of doorway modes shows a linearly correlation to the impact sensitivities derived from drop hammer tests. This result is in agreement with several previous works. Besides, it is also noted in our study that in those secondary explosives with similar molecular structure and similar molecular weight, the correlation between the impact sensitivity and the number of doorway modes is very high.

Bulk black phosphorus (BP) consists of puckered layers of phosphorus atoms. Few-layer BP, obtained from bulk BP by exfoliation, is an emerging candidate as a channel material in post-silicon electronics. A deep understanding of its physical properties and its full range of applications are still being uncovered. In this paper, we present a theoretical and experimental investigation of phonon properties in few-layer BP, focusing on the low-frequency regime corresponding to interlayer vibrational modes. We show that the interlayer breathing mode A3g shows a large redshift with increasing thickness; the experimental and theoretical results agreeing well. This thickness dependence is two times larger than that in the chalcogenide materials such as few-layer MoS2 and WSe2, because of the significantly larger interlayer force constant and smaller atomic mass in BP. The derived interlayer out-of-plane force constant is about 50% larger than that in graphene and MoS2. We show that this large interlayer force constant arises from the sizable covalent interaction between phosphorus atoms in adjacent layers, and that interlayer interactions are not merely of the weak van der Waals type. These significant interlayer interactions are consistent with the known surface reactivity of BP, and have been shown to be important for electric-field induced formation of Dirac cones in thin film BP., Comment: Nano Letters, 2015

In this paper, a back-propagation neural network has been utilized to study on the correlation between impact sensitivity and molecular properties of 33 nitramine molecules. By using density functional theory method B3P86/6-31G**, all the molecular properties have been calculated. Eight different sets of molecular properties, including (HOMO−LUMO)*BDE, E, BDE/E, HOMO−LUMO, BDE*μ, R 2, ΔE, and BDE, have been used to train and test the network. Based on the test results, the correlation order between the molecular properties and impact sensitivity has been achieved. The correlation order shows that the input set with the descriptor ΔE(atomization energy) can obtain better results than any other descriptor for nitriamines, which surely accounts for a comparatively stronger correlation between ΔE(atomization energy) and impact sensitivity for nitramines we have studied in this work.

The bond dissociation energy (BDE) for removal of the NO2 group for eleven CHNO nitro-containing explosive molecules is studied to find its correlation with impact sensitivity. The BDE for removal of the NO2 group in nitroaromatic molecules with nitro alkyl, and esters with nitro alkyl, is calculated using the B3LYP method of Density Functional Theory with the 6-31G* basis set. The relationship between the impact sensitivities and the weakest C-NO2 bond dissociation energy values is examined. The results indicate a nearly linear correlation between the impact sensitivity and the ratio of the BDE value to the total molecular energy.

Density functional theory calculations have shown that the open-shell metal-carbide endofullerene Sc3C2@C80 has the valence state (Sc3+)3(C2)(3-)@C80(6-). A lot of low-lying isomers differing in geometries and locations of the endohedral [(Sc3+)3(C2)(3-)] cluster have been located, indicating unusual dual intramolecular dynamic behaviors of this endofullerene at room temperature. The electrochemical redox properties of this endofullerene have been elucidated in terms of electronic structure theory. Its redox states are found to follow the general charge-state formula (Sc3+)3C2(3-q)-@C80(6-) (q is the charge of the whole molecule ranging from +1 to -3), demonstrating the high charge flexibility of the endohedral metal-carbide cluster. The structure of the endohedral [(Sc3+)3C2(3-q)-)] cluster varies with the redox processes, shifting from a planar structure (for q = 0 and -1) to a trifoliate structure (for q = +1, -2, -3).

We report the first detailed density functional theory study on the mechanisms of initial propane activation on molybdenum oxides. We consider 6 possible mechanisms of the C-H bond activation on metal oxides, leading to 17 transition states. We predict that hydrogen abstraction by terminal Mo=O is the most feasible reaction pathway. The calculated activation enthalpy and entropy are 32.3 kcal/mol and -28.6 cal/(mol/K), respectively, in reasonably good agreement with the corresponding experimental values (28.0 kcal/mol and -29.1 cal/(mol/K)). We find that activating the methylene C-H bond is 4.7 kcal/mol more favorable than activating the methyl C-H bond. This regioselectivity is correlated with the difference in strength between a methylene C-H bond and a methyl C-H bond. Our calculations suggest that a combined effect from both the methylene and the methyl C-H bond cleavages leads to the experimentally observed overall kinetic isotopic effects from propane to propylene on the MoO(x)/ZrO(2) catalysts.

The covalent attachment of diacetylene (HC C–C CH) and the formation of a C C–C C structure on Si(1 0 0) have been investigated using high-resolution electron energy loss spectroscopy (HREELS) and density functional theory (DFT) calculations. The HREELS spectrum of the chemisorbed monolayer shows the coexistence of C sp –H and C sp2 –H stretching modes coupled with the concurrent observation of the C C and C C stretching modes. The experimental results unambiguously demonstrate a [2 + 2]-like cycloaddition mechanism for diacetylene chemisorption on Si(1 0 0) through the binding between one of the C C groups and a Si dimer, consistent with the prediction of DFT calculations.

The structural, electronic and spectroscopic properties of a series of small neutral polycumulenic clusters XC n X ( n =1–8; X=O, S, Se) have been investigated by means of ab initio methods and density functional theory. The theoretical results revealed the following: (i) C n O 2 , C n S 2 and C n Se 2 clusters possess symmetric linear structures and exhibit drastic odd/even alternation in some structural parameters, such as bond lengths, rotational constants and so on; (ii) The energies differences of adjacent clusters also exhibit drastic odd/even parity, that is, ΔE n of C n X 2 with odd n is lower than that of even-numbered ones, indicating that the former is more stable; (iii) The above-mentioned alternation effect reduces with the growth of the carbon chain and, meanwhile, is weakened following the sequence: C n O 2 >C n S 2 >C n Se 2 . (iv) These molecules are in favor of losing CX unit, among the eight possible dissociation channels that lose C, C 2 , C 3 , CX, C 2 X 2 , CX 2 , X or X 2 fragments.

An energy decomposition scheme is proposed for understanding of the relative low binding energy of the [4+2] cycloaddition of benzene on the Si(001)-2´ 1 surface. By means of density functional cluster model calculations, this scheme is demonstrated to be applicable to some other 6- and 5-member ring aromatic compounds, giving a trend that the binding energy of the [4+2] cycloaddition products of those aromatic compounds on the Si(001) surface depends strongly on their resonance energy.

The adsorption, isomerization, and decomposition of HCN on Si(100)-2 × 1 surface have been investigated by means of a density functional theory calculation using a double-dimer cluster model. The results revealed that both HCN and its HNC isomer can be readily adsorbed on a Si−Si dimer either dissociatively or molecularly in an end-on and a side-on configuration. Side-on adsorption occurs by the cycloaddition of the C⋮N group on to the Si−Si dimer, whereas dissociative adsorption gives rise to H(a) and CN(a) adspecies initially via the end-on configuration on the same dimer or across the two dimers. Adsorbate−adsorbate interactions and reactions have also been studied with two HCN molecules. For the end-on adsorption, the first HCN(a) exerts a significant effect on the adsorption geometry of the second HCN. In particular, a synergetic effect has been observed for the parallel adsorption of two HCNs with their CN groups bridging across the two dimers. For the side-on adsorption, the adsorbate−adsorbate int...

Bond dissociation energies for removal of nitrogen dioxide groups in 10 aliphatic nitro compounds, including nitromethane, nitroethylene, nitroethane, dinitromethane, 1-nitropropane, 2-nitropropane, 1-nitrobutane, 2-methyl-2-nitropropane, nitropentane, and nitrohexane, are calculated using the highly accurate complete basis set (CBS-Q) and the three hybrid density functional theory (DFT) methods B3LYP, B3PW91 and B3P86 with 6-31G** basis set. By comparing the computed bond dissociation energies and experimental results, we find that the B3LYP/6-31G** and B3PW91/6-31G** methods are incapable of predicting the satisfactory bond dissociation energy (BDE). However, B3P86/6-31G** and CBS-Q computations are capable of giving the calculated BDEs, which are in extraordinary agreement with the experimental data. Nevertheless, since CBS-Q computational demands increase rapidly with the number of containing atoms in molecules, larger molecules soon become prohibitively expensive. Therefore, we suggest to take the B3P86/6-31G** method as a reliable method of computing the BDEs for removal of the NO2 groups in the aliphatic nitro compounds.

Photodetachment of AgX(-) (X = Cl, Br, I) and AuCl(-) is studied by a photoelectron velocity map imaging technique and theoretical calculations. Photoelectron spectra (PES) and photoelectron angular distributions (PADs) were obtained. The vibrationally resolved spectra provided approximately equal electron affinities (EAs) for AgX: 1.593(22) eV for AgCl, 1.623(21) eV for AgBr, and 1.603(22) eV for AgI, respectively. Franck-Condon simulations of these spectra gave the equilibrium bond lengths and vibrational frequencies of the title anions. Relativistic density functional theory (DFT) calculations using BLYP, PW91, PBE, and BP86 functionals have been performed to predict the EAs of the AgX (X = Cl, Br, I) molecules. The computed EAs at the BP86 level of theory are in good agreement with the experimental values. Energy partitioning analyses (EPA) at the BP86(ZORA)/QZ4P level of theory of both anions and their neutrals were reported.

The 31P NMR chemical shifts of adsorbed trimethylphosphine oxide (TMPO) and the configurations of the corresponding TMPOH+ complexes on Bronsted acid sites with varying acid strengths in modeled zeolites have been predicted theoretically by means of density functional theory (DFT) quantum chemical calculations. The configuration of each TMPOH+ complex was optimized at the PW91/DNP level based on an 8T cluster model, whereas the 31P chemical shifts were calculated with the gauge including atomic orbital (GIAO) approach at both the HF/TZVP and MP2/TZVP levels. A linear correlation between the 31P chemical shift of adsorbed TMPO and the proton affinity of the solid acids was observed, and a threshold for superacidity (86 ppm) was determined. This threshold for superacidity was also confirmed by comparative investigations on other superacid systems, such as carborane acid and heteropolyoxometalate H3PW12O40. In conjunction with the strong correlation between the MP2 and the HF 31P isotropic shifts, the 8T cluster model was extended to more sophisticated models (up to 72T) that are not readily tractable at the GIAO-MP2 level, and a 31P chemical shift of 86 ppm was determined for TMPO adsorbed on zeolite H-ZSM-5, which is in good agreement with the NMR experimental data.

A systematic DFT investigation has been conducted to explore the structures and electronic properties of the metal-carbide endofullerenes M2C2 @ C78 (M = Ti, Zr, Hf) at the PBE/DNP level of theory. The theoretical calculations predicted the following: (i) this series of endofullerenes have the valence states [M4+]2C2(2-) @ C78(6-) (ii) the structure of the [M2C2](6+) cluster encapsulated in the C78(6-) (D3h) cage varies with the increasing of the ionic radius of M4+, i.e., from a linear M-C [triple bond] C-M geometry for M = Ti, through a zigzag geometry for M = Hf to a side-on binding mode for M = Zr; (iii) M2C2 @ C78 (M = Zr, Hf) should display interesting intramolecular dynamic behavior at room temperature, i.e., the encapsulated C2(2-) moiety can rotate freely around the C3-axis of the C78(6-) (D3h) cage; (iv) the [Ti2C2]6+ in the lightest Ti2C2 @ C78 is far more fixed by adopting the linear Ti-C - C-Ti geometry; (v) the order for their ionization potentials is Ti2C2 @ C78 < Hf2C2 @ C78 << Zr2C2 @ C78, whereas their EAs follow the order: Ti2C2 @ C78 < Hf2C2 @ C78 approximately Zr2C2 @ C78. The predicted redox properties of these endofullerenes suggest that Zr2C2 @ C78 is synthetically as approachable as Hf2C2 @ C78.

Stimulated by the recent preparation and characterization of the first [50]fullerene derivative, decachlorofullerene[50] (Science 2004, 304, 699), we have performed a systematic density functional study on the electronic and spectroscopic properties of C(50), its anions and derivatives such as C(50)Cl(10) and C(50)Cl(12). The ground state of C(50) has D(3) symmetry with a spheroid shape, and is highly aromatic; the best D(5h)C(50) singlet is nonaromatic. Both D(3)() and D(5h)() isomers of C(50) have high electron affinities and can be reduced easily. Due to the unstable fused pentagon structural features, C(50) is chemically labile and subject to addition reactions such as chlorination, dimerization and polymerization. The equatorial pentagon-pentagon fusions of D(5h)C(50) are active sites for chemical reactions; hence, D(5h)C(50) may behave as a multivalent group. The computed IR, Raman, (13)C NMR and UV-vis spectra of the D(5h)C(50)Cl(10) molecule agree well with the experimental data. Finally, D(5h)C(50)Cl(10) is predicted to have a high electron affinity and, hence, might serve as an electron-acceptor in photonic/photovoltaic applications. The geometry and (13)C NMR chemical shifts of C(50)Cl(12) were computed to assist further isolation experiments.

Photodetachment of platinum carbonyl anions Pt(CO)(n)(-) (n = 1, 3) had been previously investigated using traditional photoelectron spectroscopy (PES) [G. S. Icking-Konert, H. Handschuh, G. Ganteför, and W. Eberhardt, Phys. Rev. Lett. 76, 1047 (1996); B. Chatterjee, F. A. Akin, C. C. Jarrold, and K. Raghavachari, J. Chem. Phys. 119, 10591 (2003)]. Here, we studied Pt(CO)(n)(-) (n = 1-3) using photoelectron velocity-map imaging method and extensive theoretical calculations. Vibrationally resolved spectra from photoelectron imaging experiments allow determination of the electron affinities of Pt(CO)(n), which are 1.196 ± 0.034, 0.930 ± 0.042, and 1.253 ± 0.032 eV for n = 1, 2, and 3, respectively. Two vibrational progressions are resolved for the ground states of Pt(CO) and Pt(CO)(3), while only one is resolved for that of Pt(CO)(2). The frequencies are determined to be 2089 ± 91 and 581 ± 21 cm(-1) for Pt(CO), 2173 ± 115 cm(-1) for Pt(CO)(2) and 2119 ± 88 and 444 ± 18 cm(-1) for Pt(CO)(3). Results from density functional theory and ab initio calculations agreed well with the experimental observations. The spectra were well reproduced by Franck-Condon fitting on the basis of the optimized geometries and the theoretical frequencies. The well-resolved PES also provided valuable benchmarks for various density functionals (B3LYP, BP86, and PW91PW91) for the platinum carbonyls.

The plasmon resonances and electron transport in linear sodium atomic chains are investigated using time-dependent density functional theory. The dipole response and dynamic conductance are obtained as a function of inter-atomic distance d and the chain length, under an impulse excitation polarized along the chains axis. We found that the current enhancement associated with the plasmon-induced field enhancement is mainly due to plasmon excitation of the hybridized bonding dipolar plasmons (BDP) mode. And the high energy plasmon modes are relatively weaker and are more delocalized in space than the BDP mode. The intensity of the dipole response and the current show an opposite tendency as the d is decreased while a same tendency is found as the number of atom increased. This can be understood from the competition between global quantization and local atomic confinement.

The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been calculated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method within the generalised gradient approximation (GGA) for the exchange–correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on electronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers–Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant (1 and 2, respectively) and the refractive index (n); and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.

Endohedral metallofullerenes (EMFs) with a trapped cluster size larger than four are rather scarce. Inspired by a recent experimental observation, we explored the possibility of encapsulating an unusual Sc(3)NC unit in three representative fullerene cages, namely, C(68), C(78) and C(80), by means of density functional computations. The geometries, electronic and electrochemical redox properties of the corresponding EMFs, Sc(3)NC@C(2n) (2n = 68, 78 and 80), were investigated. These novel EMFs all have very favorable binding energies, implying a considerable possibility for experimental realization. The recently observed m/z = 1121 peak in the mass spectroscopy was characterized as Sc(3)NC@C(80). Notably the lowest-energy isomer of Sc(3)NC@C(78) has a non-IPR C(78) outer cage, the possibility to accommodate five atoms inside a fullerene as small as C(68) is also intriguing. Moreover, the intracluster and metal-cage covalent interactions were revealed by a quantum theory of atoms in molecules study. Infrared absorption spectra and (13)C nuclear magnetic resonance spectra were also computed to assist future experimental characterization.

We employ ab initio plane-wave pseudopotential density functional theory to calculate the coordinates， equilibrium lattice parameters，bulk modulus，shear modulus and elastic constant of PtN2，and those calculated results agree well with the other experimental data and the published theoretical data. The curve of volume dependence of energy indicates the energy of STAAstructure is lower than that of pyrite structure. According to our result and the experimental criterion raised by Pugh, we come to the conclusion that the PtN2 is a very hard and fragile material. But when the pressure increases, the PtN2 becomes malleable gradually. It is revealed that the pyrite structure of the PtN2 is a semiconductor and the STAA structure of the PtN2 is a conductor by analyzing their density of states and band structure.