Journal of Theoretical and Computational Chemistry

To understand how the intermetallic phases of Cu–Sc influence the thermal stability and mechanical strength of Cu–Sc alloys, thermodynamic and mechanical characters of the Cu–Sc alloy have been calculated by first-principles. The lattice parameters of Cu₄Sc phase are obtained by calculated and the CuSc phase is found to be the most stable phase based on formation energies. In the binary Cu–Sc alloy, the shear moduli of Cu₄Sc and Cu₂Sc phases along the [100](001) crystal orientation are easier than those along the [100](010) crystal orientation, respectively. Pure Cu phase acts as the most stiffness phase while $\alpha$Sc phase has the lowest stiffness. Cu₄Sc phase possesses the best plasticity while CuSc phase possesses the worst plasticity. Cu₄Sc phase is the most ductile phase while $\alpha$Sc phase is the most brittle phase. From the partial density of states, the valence bands of binary Cu–Sc phases are dominated by the Sc-$d$ states.

The pyrazole compounds 4-(3-(2-amino-3,5-dibromophenyl)-1-(4-substitutedbenzoyl)-4,5-dihydro-1H-pyrazol-5-yl) benzonitriles (4–6) have been synthesized and characterized by elemental, IR, ¹HNMR spectral methods. In addition, the synthesized compounds were subjected to density functional theory for further understanding of the molecular architecture and optoelectronic properties. The optimized geometric parameters were in support of the corresponding experimental values. The FT-IR spectra of 4–6 have been investigated extensively using DFT employing B3LYP/6-31G (d,p) level theory. The molecular electrostatic potential analysis has been utilized to identify reactive sites of title compounds. Natural bonding orbital analysis proved the inter- and intra-molecular delocalization and acceptor–donor interactions based on the second-order perturbation interactions. The calculated band gap energies revealed that charge transfer occurs within the molecule. The polarizability and hyperpolarizability were calculated which show that compounds posses nonlinear optical nature.

The equilibrium structures, stabilities, magnetic, and spectroscopic properties of small-sized Al_xZr_y ($x+y\le 9$) alloy clusters have been systematically investigated within the framework of density functional theory. We found that the structures of bimetallic clusters prefer to form the same motif as their corresponding pure Al or Zr clusters and chirality turns up in mixed clusters with $x+y=6,8$ and 9. Computations of VCD and VROA spectra confirmed the chirality of these clusters. For a given cluster size, the most favorable mixing occurs when the ratio of Al:Zr is approximatively equal to 1. The total magnetic moments depend not only on the configuration but also on the composition of the clusters.

In this work, a detailed vibrational analysis of L-(-)-xylose molecule has been carried out. The geometrical parameters and anharmonic spectrum have been calculated and compared with XRD, FTIR (4000–400cm${}^{-1}$) and FT-Raman (4000–50cm${}^{-1}$) observed data. The simulated data along with IR and Raman intensities were calculated using DFT/B3LYP level of theory in combination with 6-311$++$G(d,p) basis set. The experimental and theoretical results are found to be in a good agreement with each other. Moreover, thermodynamic properties, molecular electrostatic potential (MEP) and natural bond orbital (NBO) analysis of L-(-)-xylose are also reported. The calculated HOMO and LUMO energies confirm the charge transfer within the molecule.

The computational investigations on 1:1 complexes of the nitrogen trifluoride (NF${}_3)$ species with the nitroxyl (HNO) species have been carried out, which reveal the existence of the nine complexes on the singlet potential energy surface (PES). The atoms in molecules (AIM) theory and the electron localization function (ELF) along with the identification of noncovalent interaction (NCI) regions and the investigation of electron transfer of all the obtained complexes have been carried out to provide suitable insight into the electronic and structural properties of these complexes. The calculated results reveal that the N-atom of the NF₃ species and the O-atom of the HNO species have more key roles compared with the F-atom of the NF₃ species and the N-atom of the HNO species in the obtained complexes.

Cocrystal explosive is getting more and more attention in high energy density material field. Different molar ratios of 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20)/1-Methyl-4,5-dinitro-1H-imidazole (MDNI) cocrystal were studied by molecular dynamics (MD) simulation and quantum-chemical density functional theory (DFT) calculation. Binding energy of CL-20/MDNI cocrystal and radial distribution function (RDF) were used to estimate the interaction. Mechanical properties were calculated to predict the elasticity and ductility. The length and bond dissociation energy of trigger bond, surface electrostatic potentials (ESP) of CL-20/MDNI framework were calculated at B3LYP/6-311$++$G(d,p) level. The results indicate that CL-20/MDNI cocrystal explosive might have better mechanical properties and stability in a molar ratio 3:2. The N–NO₂ bond becomes stronger upon the formation of intermolecular H-bonding interaction. The surface electrostatic potential further confirms that the sensitivity decreases in cocrystal explosive in comparison with that in isolated CL-20. The oxygen balance (OB), heat of detonation ($Q)$, detonation velocity ($D)$ and detonation pressure ($P)$ of CL-20/MDNI suggest that the CL-20/MDNI cocrystal possesses excellent detonation performance and low sensitivity.

Poly (ADP-ribose) polymerase-1 (PARP-1) reverses DNA damage by repairing DNA nicks and breaks in the normal cellular environment. However, during abnormal conditions like stroke and other neurological disorders, overactivation of PARP-1 leads to neuronal cell death via a caspase-independent programmed cell death pathway. Strategies involving inhibition or knockout of PARP-1 have proved beneficial in combating neuro-cytotoxicity. In this study, we performed in-silico analysis of 27 phytochemicals of Withania somnifera (Ashwagandha), to investigate their inhibition efficiency against PARP-1. Out of 27 phytochemicals, we report 12 phytochemicals binding to the catalytic domain of PARP-1 with an affinity higher than FR257517, PJ34 and Talazoparib (highly potent inhibitors of the enzyme). Among these 12 compounds, five phytochemicals namely Stigmasterol, Withacnistin, Withaferin A, Withanolide G and Withanolide B show an exceptionally high binding affinity for the catalytic domain of PARP-1 and bind to the enzyme with similar hydrogen bond formation and hydrophobic interaction pattern as their inhibitors. All of these phytochemicals are BBB permeable so that they can be further developed into potential future neuro-therapeutic drugs against neurodegenerative disorders involving neuronal cell death.

This work consists of an investigation, using current methods of quantum chemistry and, at first, on the basis of the available experimental results, about the new mechanisms of the reaction between ozone and hydrogen cyanide (HCN) in gaseous phases. Three possible reaction pathways which we have determined as the most probable and, all three, leading exactly to the same products, are proposed here. For each of these pathways, several steps for which we performed a kinetic study were identified in the singlet potential energy surface. To confirm the proposed mechanisms, we have achieved a study including the intrinsic reaction coordinate (IRC), the topological analysis of atoms in molecule and the harmonic vibrational frequencies calculations. The obtained results reveal that the final products have considerable thermodynamic stability and this reaction is exothermic in standard conditions.

This communication addresses unsteady squeezing flow of second grade liquid. NonFourier heat flux model is implemented to discuss heat transfer features subject to heat generation/absorption. Homogeneous–heterogeneous reactions are addressed. Firstly, the problems are nondimensionalized by suitable variables and then solutions for strong nonlinear systems are presented. Convergence region is particularly determined for obtained solutions. Statistical declaration and probable error for drag force are computed. Velocity is found to decay for larger estimation of fluid parameter while thermal and concentration fields are enhanced for higher heat generation and squeezing parameters.

The hydrogen adsorption properties of Ti and Ni atoms as media on single-walled carbon nanotube (SWCNT) have been studied by density functional theory (DFT) incorporating a pragmatic method to correctly describe van der Waals interactions. The results show that both Ti and Ni atoms can reliably adhere to single-walled carbon nanotube, respectively, making strong TM$-$C bonds. Meantime, it is found that the average adsorption energies of H₂ by Ti and Ni atoms are decreased with the increase of the amount of H₂ adsorption. Ti or Ni atoms can bind up to no more than six H₂ molecules on a carbon nanotube. It is inferred that these transition metals (TMs) can adsorb molecular hydrogen through likely Kubas-type interaction. By comparing the interaction energies among TM and H atoms, it can be identified that the hydrogen adsorption properties of Ti atoms are superior to those of Ni atoms at certain conditions. The present investigation is useful in the wider development of carbon-based nanomaterials as potential high-capacity H₂ storage media.

The most stable structure of 5-substituted uracil base pairs and metal-mediated-5-substituted uracil complexes are determined. Density functional theory (DFT) method is used in the calculations which are carried out both in vacuum and water. LANL2DZ and 6–311$++$G(d,p) basis sets are used for metals and the rest atoms, respectively. Effects on frontier molecular orbitals and energy gaps of substituents in 5-position of uracil base pairs in vacuum and water are found. Conductivity of base pairs or complexes are investigated for single nanowires studied by band theory. It is expected that this study will be an example for future studies that require new nanotechnological applications.