Theoretical Research on Structure and Infrared Spectra of the 9-Methacrylate Carbazole Molecule

Using the quantum chemical density functional theory method in the Gaussian03W package, the spatial configuration of this compound is optimized by using B3LYP/6-31G(d) as the base group, in which the data of bond length, bond angle and spatial dihedral angle of the compound molecule are obtained. Based on the optimized stable structure, the infrared vibration frequency of the molecule is calculated, and the infrared spectrum is drawn. There is no imaginary frequency in the calculation results of frequency value, which indicates that the optimized configuration of 9-methacryloyl carbazole molecule is reasonable, and the peak position of infrared spectrum is assigned.

Effect of Alkali Atom Doping on the Electronic Structure and Aromatic Character of Planar and Quasi-Planar Al13+ Clusters

A set of three Al13+ clusters, one perfectly planar and two quasi-planar structures have been recently reported by our group [Guin et. al. Journal of Molecular Graphics and Modeling, 2020, 97, 107544]. One of the quasi-planar structures is true minima (GS) with zero imaginary frequency and another one is transition state structure (TS) with one imaginary frequency, whereas the perfectly planar structure has three imaginary frequencies. All three posses bilaterally symmetry with identical structural features - a set of ten aluminium atoms encircle a triangular core and also this set of three aluminium cluster is a rare example of a metallo-aromatic system in which highly anti-aromatic islands are embedded in an aromatic sea. One of the atoms of the central triangle lies on the symmetry axis and is crucial for the stability of these clusters. In the present study, we have explored the effect of doping alkali atoms (Li, Na and K) at this pivotal site of the cluster with an aim to understand the structural stability and the effect on the aromatic character as compared to the parent clusters. Besides the electronic structural analysis, NICS and ELF studies have also been carried out to characterize the aromatic nature of the doped clusters. Interestingly it has been found that even with the incorporation of the alkali atoms the bilateral symmetry of the clusters remains intact but instead of the central position the alkali atoms drift towards the periphery of the cluster along the symmetry line and equilibrate on the periphery. The dipole moment of the clusters systematically increases and the overall aromaticity of the cluster systematically decreases with the increase in the atomic number of the dopant alkali atoms.

Interacting Cubane Assisted Bi-Cytidine with COVID-19 Main Protease: In Silico Study

In silico approach, the quantum chemical computations and molecular docking simulations have been used to investigate the formation of cubane assisted cytidine (B-Cyt) derivative for examining its interactions with the COVID-19 main protease. The obtained results indicated that the new B-Cyt derivative could be stabilized without any imaginary frequency. Its orbital orbital-based electronic properties indicated that the structure could have a better interaction with the target than the singular Cyt ligand. The docking process results approved the trend, in which the value of binding energy was very much favorable regarding the singular models, and the number of interaction amino acids was increased. The idea of forming a Cyt derivative with efficient activity against COVID-19 main protease was approved here, which is very much important for protecting the patients with cancer or HIV against the COVID-19 pandemic.

Understanding the Mechanism and Selectivities of the Reaction of Meta-Chloroperbenzoic Acid and Dibromocarbene with β-Himachalene: A DFT Study

This study was performed to understand the site selectivity in the reaction between β-himachalene and meta-chloroperbenzoic acid (m-CPBA) in the first step followed by the addition of dibromocarbene (CBr2) to the main monoepoxidation product Pα formed in the first reaction. Calculations were performed using the Becke three-parameter hybrid exchange functional and the Lee–Yang–Parr correlation functional (B3LYP) with the 6-311 + G (d, p) basis set. Transition states were located by QST2, and their highlighting was validated by the existence of only one imaginary frequency in the Hessian matrix. The action of m-CPBA on β-himachalene was analyzed on the two double bonds of β-himachalene whose theoretical calculations show that the attack affects the most substituted double bond on α side containing hydrogen of ring junction. The obtained Pα product thereafter treated with dibromocarbene leads via an exothermic reaction to the six-membered ring double bond position of α-monoepoxide. The major products Pαα are kinetically and thermodynamically favored with a high stereoselectivity in perfect correlation with the experimental observations.

Reststrahlen band studies in cubic perovskite materials SmXO3 (X = Al,Co) by computational investigations

A theoretical study of SmXO3 ([Formula: see text], Co) cubic perovskites for vibrational properties and Reststrahlen band is done within the framework of Density Functional Perturbation Theory (DFPT) implemented in Quantum ESPRESSO. The vibrational properties of the Samarium-based perovskites are figured using Martins–Troullier pseudo potentials. The phonon density of states and phonon dispersion curves in first Brillouin zone are computed and discussed in which two optical phonon frequencies, [Formula: see text] and [Formula: see text], are targeted to find Reststrahlen band for these materials. No imaginary frequency was noted, which shows the structural stability of both perovskites in cubic state. Reststrahlen bandgap and Lyddane–Sachs–Teller (LST) relation for these materials are calculated using optical phonon frequencies and applications are specified. Reststrahlen band of both materials is found to exist in the Far Infra-red region (ranging from 0.3 to 6.0 THz) showing that they can be identified by throwing light of Infrared region upon them in geological applications.

EM Duality and Quasinormal Modes from Higher Derivatives with Homogeneous Disorder

We study the electromagnetic (EM) duality from 6 derivative theory with homogeneous disorder. We find that, with the change of the sign of the coupling parameter γ1 of the 6 derivative theory, the particle-vortex duality with homogeneous disorder holds better than that without homogeneous disorder. The properties of quasinormal modes (QNMs) of this system are also explored. When the homogeneous disorder is introduced, some modes emerge at the imaginary frequency axis for negative γ1 but not for positive γ1. In particular, with an increase in the magnitude of α^, new branch cuts emerge for positive γ1. These emerging modes violate the duality related to the change of the sign of γ1. With the increase of α^, this duality is getting violated more.

Graphene-like monolayer monoxides and monochlorides

Two-dimensional monolayer materials, with thicknesses of up to several atoms, can be obtained from almost every layer-structured material. It is believed that the catalogs of known 2D materials are almost complete, with fewer new graphene-like materials being discovered. Here, we report 2D graphene-like monolayers from monoxides such as BeO, MgO, CaO, SrO, BaO, and rock-salt structured monochlorides such as LiCl, and NaCl using first-principle calculations. Two-dimensional materials containing d-orbital atoms such as HfO, CdO, and AgCl are predicted. Adopting the same strategy, 2D graphene-like monolayers from mononitrides such as scandium nitride (ScN) and monoselenides such as cadmium selenide (CdSe) are discovered. Stress engineering is found to help stabilize 2D monolayers, through canceling the imaginary frequency of phonon dispersion relation. These 2D monolayers show high dynamic, thermal, kinetic, and mechanic stabilities due to atomic hybridization, and electronic delocalization.

Structural, elastic and electronic properties of new superhard orthorhombic C28

The structural, mechanical and electronic properties of recently reported superhard material C[Formula: see text] are studied by first-principles calculations. The unit cell of C[Formula: see text] is composed of 28 carbon atoms and all sp3 hybridized bonds. From 0 GPa to 100 GPa, C[Formula: see text] satisfies the mechanical stability criteria and the phonon spectrum of C[Formula: see text] has no imaginary frequency, which means that C[Formula: see text] is mechanically and dynamically stable. The results of hardness calculated show that C[Formula: see text] is a potential superhard material with the Vickers hardness of 84.0 GPa. By analyzing the elastic anisotropy, we found that elastic anisotropy of C[Formula: see text] increases with pressure. The calculations of band structure demonstrates that C[Formula: see text] is an indirect bandgap semiconductor with the gap of 4.406 eV. These analyses demonstrate C[Formula: see text] is a superhard semiconductor material.

Дисперсионные силы между металлической и диэлектрической пластинами, разделенными магнитной жидкостью

The Lifshitz theory framework is applied to determine the pressure of dispersion forces between metallic and dielectric plates separated by a thin layer of ferrofluid. Numerical computations are performed for the plates made of gold and silica glass and ferrofluid consisting of kerosene and nanoparticles of magnetite at room temperature. For this purpose we have used familiar representations for the dielectric properties of gold and silica glass along the imaginary frequency axis and obtained respective representations for magnetite and kerosene. The pressure of dispersion forces was investigated as the function of separation between the plates, of the volume fraction of magnetite particles in a ferrofluid and of their diameter. At sufficiently large separations between the plates simple analytic expressions for this pressure are derived. We discuss possible applications of the obtained results.