Electron Binding Energies of Open-Shell Species from Diagonal Electron-Propagator Self-Energies with Unrestricted Hartree-Fock Spin-Orbitals.

For closed-shell molecules, valence electron binding energies may be calculated accurately and efficiently with electron-propagator methods that have surpassed their predecessors. Advantageous combinations of accuracy and efficiency range from cubically scaling methods with mean errors of 0.2 eV to quintically scaling methods with mean errors of 0.

Electron Propagators with an Hermitian, Intermediately Normalized Superoperator Metric Applied to Vertical Electron Affinities.

New-generation electron propagator methods for calculating electron detachment energies of closed-shell molecules and anions have surpassed their predecessors' accuracy and computational efficiency. Derived from an Hermitian, intermediately normalized superoperator metric, these methods contain no adjustable parameters. To assess their versatility, a standard set (NIST-50-EA) of 50 vertical electron affinities of small closed-shell molecules based on NIST reference data has been created.

New-generation electron-propagator methods for vertical electron detachment energies of molecular anions: benchmarks and applications to model green-fluorescent-protein chromophores.

electron-propagator calculations continue to be useful companions to experimental investigations of electronic structure in molecular anions. A new generation of electron-propagator methods recently has surpassed its antecedents' predictive accuracy and computational efficiency. Interpretive clarity has been conserved, for no adjustable parameters have been introduced in the preparation of molecular orbitals or in the formulation of approximate self-energies.

New-Generation Electron-Propagator Methods for Molecular Electron-Binding Energies.

A new generation of electron-propagator methods for the calculation of electron binding energies has surpassed its antecedents with respect to accuracy, efficiency, and interpretability. No adjustable parameters are introduced in these fully procedures. Numerical tests versus several databases of valence, vertical electron binding energies of closed-shell molecules and atoms have been performed.

New-Generation Electron-Propagator Methods for Calculations of Electron Affinities and Ionization Energies: Tests on Organic Photovoltaic Molecules.

A new generation of electron-propagator self-energies recently superseded its antecedents' accuracy and computational efficiency in calculating vertical ionization energies (VIEs) of closed-shell molecules. (See 204107, 4927, 124109.) No adjustable parameters were introduced in the generation of reference orbitals or in the construction of self-energies.

A new generation of non-diagonal, renormalized self-energies for calculation of electron removal energies.

A new generation of diagonal self-energies for the calculation of electron removal energies of molecules and molecular ions that has superseded its predecessors with respect to accuracy, efficiency, and interpretability is extended to include non-diagonal self-energies that permit Dyson orbitals to be expressed as linear combinations of canonical Hartree-Fock orbitals. In addition, an improved algorithm for renormalized methods eliminates the convergence difficulties encountered in the first studies of the new, diagonal self-energies. A dataset of outer-valence, vertical ionization energies with almost full-configuration-interaction quality serves as a standard of comparison in numerical tests.

Examining the level of public awareness on the Sustainable Development Goals in Africa: An empirical evidence from Ghana.

Nations which are part of the United Nations are required to institute appropriate measures to fulfil the vision of the Sustainable Development Goals (SDGs). However, for this to be possible, all stakeholders including the general public need to be fully aware of the SDGs. This research examined the level of public awareness about the SDGs among Ghanaians based on the views of 431 respondents.

Electron Propagator Theory of Vertical Electron Detachment Energies of Anions: Benchmarks and Applications to Nucleotides.

A new generation of electron-propagator self-energy approximations that are free of adjustable parameters is tested on a benchmark set of 55 vertical electron detachment energies of closed-shell anions. Comparisons with older self-energy approximations indicate that several new methods that make the diagonal self-energy approximation in the canonical Hartree-Fock orbital basis provide superior accuracy and computational efficiency. These methods and their acronyms, mean absolute errors (in eV), and arithmetic bottlenecks expressed in terms of occupied (O) and virtual (V) orbitals are the opposite-spin, non-Dyson, diagonal second-order method (os-nD-D2, 0.

Double Rydberg anions, Rydberg radicals and micro-solvated cations with ammonium-water kernels.

Highly accurate electron-propagator and coupled-cluster methods are employed to predict the vertical electron attachment energies (VEAEs) of NH(HO) ( = 1-4) cationic clusters. The VEAEs decrease with increasing and the corresponding Dyson orbitals are diffused over peripheral, non-hydrogen bonded protons. Clusters formed from NH double Rydberg anions (DRAs) and stabilized by hydrogen bonding or electrostatic interactions are studied through calculations on NH(HO) complexes and are compared with more stable H(NH)(HO) isomers.

Electron Propagator Self-Energies versus Improved GW100 Vertical Ionization Energies.

electron propagator (EP) methods that are free of adjustable parameters in their self-energy formulae and in the generation of their orbital bases have been applied to the calculation of the lowest vertical ionization energies (VIEs) of the GW100 set. An improved set of standard results accompanied by irreducible representation assignments has been produced indirectly with coupled-cluster singles and doubles plus perturbative triples, i.e.

Mechanistic elucidation of the tandem Diels-Alder/(3 + 2) cycloadditions in the design and syntheses of heterosteroids.

The potential of azasteroids as novel drug candidates has prompted numerous studies towards the syntheses of heterosteroidal skeletons. The preparation of novel azasteroidal compounds and the modification of substituents on their steroidal skeletons might provide excellent congeners with useful biological properties. We present herein computational investigations on the Diels-Alder/(3 + 2) tandem sequential cycloaddition reaction of 21 distinctive derivatives of furylcinnamate with phenyl azides.

A new generation of diagonal self-energies for the calculation of electron removal energies.

A new generation of diagonal self-energy approximations in ab initio electron propagator theory for the calculation of electron removal energies of molecules and molecular ions has been derived from an intermediately normalized, Hermitized super-operator metric. These methods and widely used antecedents such as the outer valence Green's function and the approximately renormalized partial third order method are tested with respect to a dataset of vertical ionization energies generated with a valence, triple-ζ, correlation-consistent basis set and a converged series of many-body calculations whose accuracy approaches that of full configuration interaction. Several modifications of the diagonal second-order self-energy, a version of GW theory based on Tamm-Dancoff excitations and several non-diagonal self-energies are also included in the tests.

Electron binding energies and Dyson orbitals of OH clusters: Double Rydberg anions, Rydberg radicals, and micro-solvated hydronium cations.

Ab initio electron propagator methods are employed to predict the vertical electron attachment energies (VEAEs) of OH (HO) clusters. The VEAEs decrease with increasing n, and the corresponding Dyson orbitals are diffused over exterior, non-hydrogen bonded protons. Clusters formed from OH double Rydberg anions (DRAs) and stabilized by hydrogen bonding or electrostatic interactions between ions and polar molecules are studied through calculations on OH (HO) complexes and are compared with more stable H(HO) isomers.

Unveiling the molecular mechanisms of the cycloaddition reactions of aryl hetaryl thioketones and C,N-disubstituted nitrilimines.

Many synthetic routes to constructing biologically active heterocyclic compounds are made feasible through the (3 + 2) cycloaddition (32CA) reactions. Due to a large number of possible combinations of several heteroatoms from either the three-atom components (TACs) or the ethylene derivatives, the potential of the 32CA reactions in heterocyclic syntheses is versatile. Herein, the cycloaddition reaction of thiophene-2-carbothialdehyde derivatives and C,N-disubstituted nitrilimines have been studied through density functional theory (DFT) calculations at the B3LYP/6-311G(d,p) level of theory.

Peri-, Chemo-, Regio-, Stereo- and Enantio-Selectivities of 1,3-dipolar cycloaddition reaction of C,N-Disubstituted nitrones with disubstituted 4-methylene-1,3-oxazol-5(4H)- one: A quantum mechanical study.

The peri-, chemo-, regio-, stereo- and enantio-selectivities of 1,3-dipolar cycloaddition reaction of C,N-disubstituted nitrones with disubstituted 4-methylene-1,3-oxazol-5(4H)-one have been studied using density functional theory (DFT) at the M06-2X/6-311G (d,p) level of theory. The 1,3-dipole preferentially adds chemo-selectively across the olefinic bond in a (3 + 2) fashion forming the corresponding spirocycloadduct. The titled reaction occurs with poor enantio- and stereo-selectivities, but a high degree of regio-selectivity is observed for the addition of the 1,3-dipole across the dipolarophile.

The mechanisms of gallium-catalysed skeletal rearrangement of 1,6-enynes - Insights from quantum mechanical computations.

The transition metal-catalysed skeletal reorganization of 1,6-enynes can lead to three types of products - a type I product occurring via the cleavage of the alkene C-C bonds and the migration of the terminal alkene carbon to the terminus of the alkyne; a type II product arising from cleavage of both the double and the triple bonds followed by insertion of the terminal alkene carbon into the alkyne C-C triple bond; and a type III product which is obtained when there is a cleavage of the olefinic bond followed by formation of two new bonds from each carbon to each of the acetylenic carbons. The course of these reactions is highly dependent on the metal catalyst used and type of substitution at the alkene and alkyne moieties of the enyne. In this mechanistic study of the re-organization of 1,6-enynes catalysed by GaCl, performed at the DFT M06/6-311G(d,p) level of theory, the parent reaction selectively leads to the formation of the type I product through the formation of the open cyclopropane ring.

Mechanistic studies on tandem cascade [4 + 2]/ [3 + 2] cycloaddition of 1,3,4-oxadiazoles with olefins.

The mechanism of the reaction of 1,3,4-oxadiazoles with alkenes (ethylene) and cycloalkenes (cyclobutene, cyclopentene, cyclohexene and cycloocene) have been studied computationally at the DFT M06-2X/6-311G* level. The reaction is found to proceed via a concerted [4 + 2] addition followed by nitrogen extrusion and then [3 + 2] addition in a tandem cascade fashion, which in the case of cycloalkenes leads to exo-fused or endo-fused subframes, the exo of which is kinetically and thermodynamically favored. The [4 + 2] step is the rate-determining step of the reaction.

1, 3-Dipolar cycloaddition reactions of selected 1,3-dipoles with 7-isopropylidenenorbornadiene and follow-up thermolytic cleavage: A computational study.

The mechanism, regio-, stereo-, and enantio-selectivities of the 1,3-dipolar cycloaddition reactions of 7-isopropylidenenorbornadiene (DENBD) with nitrones and azides to form pharmaceutically relevant isoxazolidine and triazole analogues have been studied computationally at the M06/6-31G(d), 6-31G(d,p), 6-311G(d,p), 6-311++G(d,p) and M06-2X/6-31G(d) levels of theory. In the reactions of DENBD with phenyl nitrones, the cycloaddition steps have low activation barriers, with the highest being 16 kcal/mol; and the Diels-Alder cycloreversion steps have generally high barriers, with the lowest being 20 kcal/mol, suggesting that the isolable products in these reactions are the bicyclic isoxazolidine cycloadducts and not the thermolytic products. This is in contrast to the reactions of DENBD with phenyl azide where the isolable products are predicted to be the thermolytic products since the Diels-Alder cycloreversion steps had relatively lower activation barriers.

Quantum chemical studies on the mechanistic aspects of tandem sequential cycloaddition reactions of cyclooctatetraene with ester and nitrones.

The mechanisms of the tandem sequential [4 + 2]/[3 + 2] and [3 + 2]/[4 + 2] cycloaddition sequences involving an ester, cyclooctatetraene (COTE), and cyclic and acyclic nitrones for the formation of a diverse range of isoxazolidine derivatives and other synthetic precursors are reported. A thorough exploration of the PES has characterized several regio-, stereo- and enantio-selective mechanistic channels involved in these reactions. A perturbation molecular orbital (PMO) analysis been employed to rationalize the results.

Computational studies on [4 + 2] / [3 + 2] tandem sequential cycloaddition reactions of functionalized acetylenes with cyclopentadiene and diazoalkane for the formation of norbornene pyrazolines.

The mechanistic pathways for the sequential tandem [4 + 2] / [3 + 2] versus [3 + 2] / [4 + 2] cycloaddition reaction of functionalized acetylenes with cyclopentadiene and dimethyl diazopropane for the formation of norbornene pyrazolines, employed in the synthesis of pharmaceutically relevant compounds, have been studied computationally with DFT at the M06-2X/6-31G(d) and M06-2X/6-31G(d,p) levels of theory. We have established that, in the reaction of the parent (unsubstituted) acetylene with cyclopentadiene and dimethyl diazopropane, the order of the tandem addition has no substantial effects in product outcomes. The same product is obtained provided the reaction components remain the same for both [4 + 2]/[3 + 2] and [3 + 2]/[4 + 2] tandem addition sequences.

Impact of combined intermittent preventive treatment of malaria and helminths on anaemia, sustained attention, and recall in Northern Ghanaian schoolchildren.

Background: The benefits of integrated control of malaria, schistosomiasis, and soil-transmitted helminth infections have not been fully explored in Ghanaian schoolchildren.

Objective: To assess the impact of co-administered artemether-lumefantrine plus albendazole, and artemether-lumefantrine plus albendazole plus praziquantel compared to albendazole plus praziquantel on anaemia, sustained attention, and recall in schoolchildren.

Design: This three-arm, open-label intervention study was carried out in Ghana among class three schoolchildren.

Evidence-based training and mentorship combined with enhanced outcomes surveillance to address the leading causes of neonatal mortality at the district hospital level in Ghana.

Objective: To evaluate the impact of a district hospital intervention focused on enhancing healthcare provider capacity to address leading causes of neonatal death: birth asphyxia, infection and prematurity.

Methods: The neonatal quality improvement initiative was launched at two intervention referral district hospitals in Ghana. Local Health and Demographic Surveillance Systems were enlisted to enhance recording of neonatal and infant deaths in the community and at the facility.

Using community health workers in community-based growth promotion: what stakeholders think.

The Nutrition and Malaria Control for Child Survival Project is a community-based growth promotion project that utilizes Community Health Workers (CHWs), referred to as Community Child Growth Promoters (CCGPs), as the principal change agents. The purpose of this study was to identify perceptions of key stakeholders about the project and the role of the CCGPs. The study employed qualitative methods: focus group discussions with CCGPs and care givers, exit interviews with care givers, and key informant interviews with health workers and CCGPs.