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A review and comparative analyses of methods for restricting the range of molecular interactions within the concept of atom-atom potentials are presented. Emphasis is placed on the problem of calculating the electrostatic energy in models with periodic boundary conditions. Numerous calculations of the thermodynamic and structural characteristics of water using parallel Monte Carlo computations have shown that the use of functional forms simulating the electric potentials of “screened charges” provides very good results.

Interpretation of X-ray photoelectron spectra (XPS) for p -nitroaniline and the nitroxide radical was carried out by the time-dependent density functional theory (TD-DFT) method using the ( Z +1) ^N-1 approximation. Consideration of satellite transitions in the interpretation of the XPS spectra leads to good agreement with experiment. The shape of the X-ray photoelectron spectra of the radicals mainly depends on the relaxation processes caused by the X-ray hole screening effect and leading to the formation of satellite lines. The structure of the satellites in the XPS spectra depends on the spin state of the system and intermolecular interaction.

Visualization pictures of collective motion of particles are presented, showing the existence of mesoscopic (of the order of tens of angstroms) vortex-like motions at time intervals of at least hundreds of picoseconds in molecular dynamics models of liquid argon.

α-³⁴S has been studied with X-ray crystallography within 100-363 K. Anisotropy of the evolution of the parameters of the orthorhombic unit cell has been examined. The absolute increase in the cell volume is 154 ų, and the relative one is 4.8%. It has been demonstrated that in the studied range the intramolecular S-S bond lengths are shortened at average by 0.006 Å on heating. At the same time, intermolecular contacts S…S shorter than the sum of van der Waals radii demonstrate average elongation of 0.097 Å.

A novel complex [Ag(ptac)]_∞ (1) (ptac = ^t BuC(O)CHC(O)CF₃) has been prepared by interaction of Ag₂O and Hptac, its structure being elucidated by single crystal X-ray diffraction. The complex has a chain polymeric structure originating from tetradentate-m-bridging coordination of the ptac ligands and interactions Ag-Cg between adjacent {Ag(ptac)} fragments. The coordination environment of the silver atom is a distorted square pyramid. The distances Ag-O are 2.362(10)-2.600(10) Å; Ag-Cg - 2.32(2) Å and 2.328(13) Å; Ag···Ag - 3.3497(13) Å and 3.3750(13) Å; the values of chelate angles OAgO fall within 64.6(4)-71.1(3)°. Under thermogravimetric experiment conditions compound 1 decomposes within temperature range 100-385°С with formation of silver metal.

Coordination nickel pyrophosphate [Ni(H₂P₂O₇)(C₁₂H₈N₂)₂]×2.5H₂O (I) is hydrothermally synthesized and characterized by single crystal X-ray diffraction. The title compound crystallizes in the triclinic system, space group P-1, with cell parameters M = 640.07, a = 10.285(2) Å, b = 10.510(3) Å, c = 12.775(3) Å, a = 88.06(2)°, b = 77.87(2)°, g = 89.26(2)°, V = 1349.2(5) ų, Z = 2, R ₁[ I > 2s( I )] = 0.0438, wR ₂[ I > 2s( I )] = 0.1244. This compound displays a new structure of ladder-like 2D layers parallel to (010) consisting of [Ni(H₂P₂O₇)(phen)₂] entities with the distorted octahedral NiN₄O₂ coordination geometry arising from two chelating 1,10-phenanthroline ligands and diphosphate [H₂P₂O₇] ligand bridged through p⋯p stacking interactions between the neighboring 1,10-phen ligands with interplanar distances of 4.425 Å and 4.525 Å. In the compound, the phen ligands bind in a bidentate fashion to the metal atoms and the ladder-like structure of the compound extends into a three-dimensional supramolecular array via hydrogen bonds (O4-H17…O5) between diphosphate groups, which delimits b axis tunnels where water molecules are located.

New complex [Pt(Ph₂bipy)Cl₂] (1) is obtained from the reaction of H₂PtCl₆×6H₂O and 4,4¢-diphenyl-2,2¢-bipyridine (Ph₂bipy) in a mixture of methanol, chloroform, and dimethyl sulfoxide. Suitable crystals of 1 for the diffraction experiment are obtained by slow evaporation of the resulted orange solution at room temperature. This complex is characterized by elemental analysis, IR, ¹H NMR, UV-Vis, and luminescence spectroscopy and its structure is studied by the single crystal X-ray diffraction method. X-ray structure determination shows that in the structure of this compound, the Pt(II) atom is four-coordinated in a distorted square-planar configuration by two nitrogen atoms from a bidentate 4,4¢-diphenyl-2,2¢-bipyridine ligand and two terminal chlorine atoms.

The newly attempted template synthesis involving 1-hydrazinocarbonylmethyl-7-bromo-5-phenyl-1,2-dihydro-3 H -1,4-benzdiazepin-2-one (Hydazepam - HHy) (1), 2-hydroxy-1-naphtaldehyde (HNf) (2) and tin tetrachloride (3) in the solution of iso -propanol has afforded a tin(IV) coordination compound with 1-[(2-hydroxy-1-naphtyl)methylenhydrazino]carbonylmethyl-7-bromo-5-phenyl-1,2-dihydro-3 H -1,4-benzdiazepin-2-one (H₂HyNf) (4) - the product of condensation of 1 with 2. The composition of the complex [Sn(HHyNf)Cl₃] (5) and its structure have been confirmed by a number of physical chemical methods. Its molecular structure has been determined by single crystal XRD. The coordination polyhedron of the tin atom is an octahedron formed by three chlorine atoms, azomethine nitrogen atom and two oxygen atoms of the carbonyl and deprotonated hydroxy group of the ligand.

The structure of a samarium(III) complex with acylhydrazone of N-(2-hydroxyphenyl)iminodiacetic acid and 5-hydroxy-3-methyl-1-phenyl-4-formylpyrazole (Н₅L) of the composition [Sm₂(Н₃L)₃]×С₂Н₅ОН×10Н₂О has been determined by single crystal X-ray diffraction. It has been found that in the dinuclear complex the coordination polyhedra have the geometry of a slightly distorted tri-capped trigonal prism and are linked with three iminodimethylene bridges arranged in a triple helix.

The structures of two novel 8-hydroxyquinoline derivatives with 1,3-tropolonic fragment in the second position of the quinoline ring have been studied as a promising new multidentate system with extended coordination capabilities .