Small Gold-Thiolate Clusters Au3(SMe)3: Benchmarking of Density Functionals and Bonding Analysis

We present a benchmark study on popular density functionals for their efficiency and accuracy in the geometry and relative stability of gold-thiolate nanoclusters taking Au3(SMe)3 isomers. We have used normalized mean absolute error (NMAE) analysis as a parameter to compare the results with the reference methods - DLPNO-CCSD(T) and RI-SCS-MP2. We have also compared the performance on the thiolate interaction energy of the stable geometries using the results from our benchmark study. One of the promising functional is PBE that shows robust performance for geometry optimization. On the other hand, M06-2X stands out as the proper choice for the relative energies of the clusters. With the selected methods, we have analyzed the gold-sulfur interaction in Au3(SMe)3 and a comparison is made with AuSMe. The bonding analysis has revealed a partial covalency between gold and sulfur atoms in general. On going from AuSMe to Au3(SMe)3, a substantial flow of charge from gold atoms to thiolate ligands as a result of the increase in gold s-d hybridization. As the s-d mixing in Au increases, the main character of Au-S interaction shifts from covalent to ionic. Hence, a covalent-charge-transfer interaction dominates in gold-sulfur bonding and gives rise to a charge-shift bonding.

Performance Prediction and Geometry Optimization for Application of Pump as Turbine: A Review

Pump as Turbine (PAT) is a technically and economically effective technology to utilize small/mini/micro/pico hydropower, especially in rural areas. There are two main subjects that influence the selection and application of PAT. On the one hand, manufacturers of pumps will not provide their characteristics under the turbine mode, which requires performance prediction methods. On the other hand, PAT efficiency is always slightly lower than that of pump, which requires further geometry optimization. This literature review summarized published research studies related to performance prediction and geometry optimization, aimed at guiding for selection and optimization of PAT. Currently, there exist four categories of performance prediction methods, namely, using BEP (Best Efficiency Point), using specific speed, loss modeling, and polynomial fitting. The using BEP and loss modeling methods are based on theoretical analysis, while using specific speed and polynomial fitting methods require statistical fitting. The prediction errors of published methods are within ±10% mostly. For geometry optimization, investigations mainly focus on impeller diameter and blade geometry. The influence of impeller trimming, blade rounding, blade wrap angle, blade profile, blade number, blade trailing edge position, and guide vane number has been studied. Among published methods, the blade rounding and forward-curved impellers are the most effective and feasible techniques.

Novel ultra-hard hexacarbon allotropes from first principles

Novel ultra-hard hexacarbon C6 allotropes are proposed based on crystal chemistry rationale and geometry optimization onto ground state structures. Similar to diamond, the orthorhombic, tetragonal and trigonal C6 are cohesive networks of C4 tetrahedra illustrated by charge density projections exhibiting sp3-like carbon hybridization. All three allotropes are identified as mechanically (elastic constants) and dynamically (phonons) stable. The electronic band structures are characteristic of insulators with large band gaps of 4 to 5 eV, like diamond. From three different models evaluating Vickers hardness HV, all new carbon allotropes are identified as ultra-hard.

Structural Characterization, DFT Geometry Optimization, Cyclic Voltammetry and Biological Assay of (Tellurite-pyridine) Mixed Ligandcomplexesof Cd(II)

This research work presents spectral characterizations (IR, 1H NMR and 13C NMR) of anionic tellurito Cd(II) complexes that prepared using cyanopyridine derivatives as a polydentate ligands. Also, X-ray based techniques involving (EDX and XRD) are applied for cadmium complexes to realize elemental composition and average crystallographic coherence. Moreover, the electrochemical studies represented on cyclic voltammetry are determined for Cd)II) in (absence/presence) of ligands to detect the role of complexation in solution measurements. All the previous experimental investigations are supported with molecular modeling of the geometric optimized structures based on density function theory (DFT) for all compounds accompanied by the calculations of different energetic parameters such as EHOMO and ELUMO. Finally, anti-microbial (antibacterial and antifungal), anti-oxidant and Bleomycin dependent DNA damage are screened for all samples to predict the influence of metal complex formation on the biological activity of pyridyl ligands besides their priority.

Genetically engineered tri-band microstrip antenna with improved directivity for mm-wave wireless application

<abstract><p>Multi-band microstrip patch antennas are convenient for mm-wave wireless applications due to their low profile, less weight, and planar structure. This paper investigates patch geometry optimization of a single microstrip antenna by employing a binary coded genetic algorithm to attain triple band frequency operation for wireless network application. The algorithm iteratively creates new models of patch surface, evaluates the fitness function of each individual ranking them and generates the next set of offsprings. Finally, the fittest individual antenna model is returned. Genetically engineered antenna was simulated in ANSYS HFSS software and compared with the non-optimized reference antenna with the same dimensions. The optimized antenna operates at three frequency bands centered at 28 GHz, 40 GHz, and 47 GHz whereas the reference antenna operates only at 28 GHz with a directivity of 6.8 dB. Further, the test result exhibits broadside radiation patterns with peak directivities of 7.7 dB, 12.1 dB, and 8.2 dB respectively. The covered impedance bandwidths when S₁₁$ \leq $-10 dB are 1.8 %, 5.5 % and 0.85 % respectively.</p></abstract>

Comparative assessment of some benzodiazepine drugs based on Density Functional Theory, molecular docking, and ADMET studies

Benzodiazepines are widely used to treat anxiety, insomnia, agitation, seizures, and muscle spasms. It works through the GABAA receptors to promote sleep by inhibiting brainstem monoaminergic arousal pathways. It is safe and effective for short-term use, and arises some crucial side effects based on dose and physical condition. In this investigation, physicochemical properties, molecular docking, and ADMET properties have been studied. Density functional theory with B3LYP/6-311G+(d,p) level of theory was set for geometry optimization and elucidate their thermodynamic, orbital, dipole moment, and electrostatic potential properties. Molecular docking and interaction calculations have performed against human GABAA receptor protein (PDB ID: 4COF) to search the binding affinity and effective interactions of drugs with the receptor protein. ADMET prediction has performed to investigate their absorption, metabolism, and toxic properties. Thermochemical data suggest the thermal stability; the docking result predicts effecting bindings and ADMET calculation disclose non-carcinogenic and relatively harmless phenomena for oral administration of all drugs.

GEOMETRY OPTIMIZATION OF COUPLING ALLIN -METFORMIN USING DFT/B3LYP MOLECULAR MODELLING TECHNIQUE

This researchpaper includes the incorporation of Alliin at various energy levels and angles With Metformin using Gaussian 09 and Gaussian view 06. Two computers were used in this work. Samples were generated to draw, integrate, simulate and measure the value of the potential energy surface by means of which the lowest energy value was (-1227.408au). The best correlation compound was achieved between Alliin and Metformin through the low energy values where the best place for metformin to bind was through (CH2-). This is considered to be very useful for the industrial application of drugs. This level of calculation was used for physical and quantum properties such as total energy, HOMO and LUMO orbitals energies, and power gap. Besides, the calculation of FT-IR spectra in the range 400-4000 cm-1 was calculated in addition to the essential vibrational frequencies and the intensity of the vibrational bands. Moreover, the chemical displacement of the 1H and 13C NMR of the compound in the ground state was studied.

Synthesis, DFT Calculations, DNA Binding and Molecular Docking Studies on Biologically Active N-((3-(4-Methoxyphenyl)-1-phenyl-1H-pyrazol-4-yl)methylene)naphthyl Derivatives

The biologically active pyrazole clubbed imino naphthyl derivatives have been designed and synthesized from 1-phenyl-3-methoxy phenyl-1H-pyrazol-4-carboxaldehyde and substituted naphthyl amines via acid catalyzed condensation reaction. All the synthesized compounds were well characterized by different spectroscopic and mass spectral techniques. The in vitro antibacterial, antifungal and antituberculosis studies were carried out. The molecular docking study was also done with the software Arguslab 4.0.1. The studied compounds showed moderate to good biological activities both experimentally and theoretically. Geometry optimization, DNA binding interaction and FMO analysis were also investigated with the help of Gaussian 16 package at B3LYP/6-31G(d,p) level.