Investigation of molecular and electronic structure of polycyclic aromatic hydrocarbons of coal tar

The molecular and electronic structure of coal tar asphaltenes was investigated. The objects of the study are asphalt resins of coking Kuzbass coal. Solution absorption spectra in the range of 310-780 nm were recorded on a СФ-2000 spectrophotometer. In the process of studying the absorption spectra of asphaltenes by optical spectroscopy, it has been found that the asphaltene fraction is a strong donor and electron acceptor. Effective ionization potential (6.64 eV), effective electron affinity (1.20 eV) and band gap width (5.44 eV) have been established. The study of the electronic structure of molecules of polycyclic aromatic hydrocarbons (PAHs), which are nuclei of molecules of asphaltenes of the "continental" type, was carried out by the method of DFT/B3LYP with the basic set 6-31+G*, using the software package GAUSSIAN. Quantum-chemical calculations have shown that the first vertical ionization potential is equal to that the first vertical ionization potential is in the range of 6.41 to 6.71 eV, affinity to the electron – from 0.79 to 1.08 eV, values of the gap zone width – from 5.33 to 5.92 eV. Dipole moments of asphaltenes (0.32 to 0.46 D) were calculated. The calculation data confirm the hypothesis of increased donor-acceptor capacity of asphalt-resin substances.

The Na2X Superalkali Species (X=SH, SCH3, OCH3,CN, N3) as Building Blocks in the Na2XY Salts (Y=MgCl3, Cl, NO2). An Ab Initio Study of the Electric Propertiesof the Na2XY Salts

Vertical and adiabatic ionization potentials of Na2X (X = SH, SCH3, OCH3, CN, and N3) superalkali molecules have been studied using the ab initio methods. The smallest vertical ionization potential was calculated for the Na2OCH3 system (4.365 eV). The Na2X molecules were found to be capable of forming stable [Na2X]+[Y]– salts with the species exhibiting various electron affinities (Y = MgCl3, Cl, NO2). The dipole moments, polarizabilities, and first-order hyperpolarizabilities of the Na2XY ionic salts were calculated and discussed. It was found that the Na2XNO2 molecules possess extraordinary large values of anisotropy of polarizabilities (in the 15.5–28.2 × 10–24 esu range) and the first-order hyperpolarizbilities (spanning the 597.8–1295.7 × 10–30 esu range).

Electronic Structure of Bimetallic FemAln (m+n=6) Clusters

Theoretical study on the electronic structure of small FemAln(m+n=6) clusters has been carried out at the BPW91 level, and the electronic structures, binding energy and vertical ionization potential of clusters were evaluated. For the stable clusters, the iron atoms gather together and form a maximum of Fe-Fe bonds, and the aluminum atoms locate around Fe core with a maximum of Fe-Al bonds. The binding energy and vertical ionization potential show that the Fe5Al, Fe4Al2 and Fe3Al3 clusters have higher stability, which results provide insight into the properties of iron-aluminides can be obtained from a finite size cluster model.

SIZE EFFECTS AND THE ROLE OF NONADDITIVE FORCES IN NEUTRAL AND ANIONIC SILVER-CLUSTER STABILITY

The precise quantum-chemical study of neutral and anionic silver clusters manifests the pronounced size effect for the vertical ionization potential (VIP), vertical detachment energy (VDE), and atomic detachment energy (ε1). The additive and nonadditive contributions to the binding energy of clusters are calculated and their role in the cluster stability is discussed.