Figure 1 - uploaded by Elena Sheka
Content may be subject to copyright.
a. Energy of singlet and triplet states as well as the total number of effectively unpaired electrons of ethylene vs C-C distance. b. Energy derivatives vs C-C distance (see text) (UHF calculations).
Source publication
The paper presents a new approach to the determination of standard spin-orbit
coupling parameters, such as the SOC constant a_SO and the Lande parameter g,
by using peculiarities of UHF results for open-shell systems. The approach is
convincingly approved for stretched ethylene and fullerene C60 as examples,
thus justifying at once a high efficacy...
Contexts in source publication
Context 1
... UHF characteristics, which accompany stretching the ethylene C-C bond up to 2Å, are shown in Fig. 1a. Equilibrium C-C distances constitute 1.326Å and 1.415Å in singlet and triplet states of the molecule, respectively. As seen in the figure, as stretching of the bond increases, energies and approach each other up to quasidegeneracy, which is characteristic for biradicals and which is necessary for an effective SOC [5]. Simultaneously, ...
Context 2
... electrons , which is zero until C-C distance reaches , starts to grow manifesting a gradual radicalization of the molecule as the bond is stretched as well as exhibiting the transformation of the molecule behavior from closed-shell to open-shell one when is overstepped. The force applied to the ethylene C-C bond under stretching is presented in Fig. 1b. At the beginning it proceeds linearly starting, however, to slow down when R is approaching . A clearly seen kink is vivid in the region. For comparison, the curve with horizontal bars presents the force caused by stretching a single C-C bond of ethane, for which constitutes 2.11Å [2], that is why the molecule remains closed-shell one ...
Citations
Abstract
The current paper is devoted to the consideration of s p 2-carbonaceous fullerenes molecules in a homogeneous magnetic field. Due to a reduction system symmetry in the magnetic field, the energy splitting gives rise dominant atomic structures in fullerene molecules with local symmetries. Spin-orbit interaction plays a crucial role in this phenomenon. The current paper is aimed at determine spin-orbit coupling parameters, as an energy E SO and a constant a SO as well as a Lande g-factor for the C60-based compounds in the magnetic field.
In this work, a thorough spectroscopic investigation is made on the molecule; Bis (thiourea) Nickel Bromide (BTNB) by recording FT-IR, FT-Raman and UV Visible spectra. The computational calculations were carried out by HF and DFT methods with 6-31++G(d, p) and 6-311++G(d, p) basis sets and the optimized geometrical parameters, vibrational fundamentals, natural bond orbitals, Frontier molecular orbital energies and NMR chemical shift have been calculated and presented in the table. The cause of change of physical and chemical properties by coordination covalent bond between metal and organic atoms has been discussed in detail. Hence, the Non Linear Optical properties of the present molecule have been studied by calculating average Polarizability and diagonal hyperpolarizability. The enhancements of physical and chemical properties of the coordination complex due to the Vander Waals bond have been interpreted. The thermodynamical parameters were calculated and these values are obtained from NIST thermodynamical program. The variation of specific heat capacity, entropy and enthalpy with respect to different temperature are displayed in the graph and are discussed. A new semiorganic nonlinear optical crystal of Bis (thiourea) Nickel Bromide (BTNB) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectrum is recorded to determine symmetries of molecular vibrations. The recording of Optical absorbance spectrum revealed that this crystal has good transparency in the visible region. The nonlinear nature of the present crystal has been confirmed by the SHG test. The BTNB crystal was analyzed by a differential thermal analysis and thermo gravimetric analysis (DTA-TGA) to obtain its thermal stability. Vickers micro-hardness test has done on the crystal and this shows that the crystal has greater physical strength.
