The E0 center formed by g-irradiation in crushed quartz has a distribution in the value of the hyperfine fine structure (hfs) constant of 29Si (nuclear spin: I ˆ 1=2) and of the g-factor. The widths of both distributions decreased after annealing. The central line due to the E0center associated with 28Si (I = 0) shows a clear narrowing as to allow the numerical simulation of the distribution of...

A simplified Hückel-type molecular-orbital (MO) model for the valence electrons of saturated hydrocarbons is proposed and the consequent eigenvalue spectrum considered. A first foundational result is obtained, which every chemist “knows”, namely that: alkanes are stable, with half their (Hückeltype MO) eigenvalues positive and half negative.

The quantum-chemical calculations on the conformational properties of 2-flouro-2-oxo- 1,3,2-dioxaphosphorinane (1), 2-choloro-2-oxo-1,3,2-dioxaphosphorinane (2) and 2-bromo- 2-oxo-1,3,2-dioxaphosphorinane (3) have been investigated by means of ab initio molecular orbital (HF/6-311+G**) and hybrid density functional theory (B3LYP/6-311+G**) based methods and Natural Bond Orbital (NBO) interpreta...

Structural and magnetic properties of purine and pyrimidine nucleotides (CMP, UMP, dTMP, AMP, GMP, IMP) were studied at different levels of ab initio molecular orbital theory. These calculations were performed at the hartree-fock level and density functional B3LYP methods. Geometries were fully optimized by following Cs symmetry restrictions. The standard 6-31G** basis set which includes polari...

We present a formalism to calculate the orbital magnetization of interacting Dirac fermions under a magnetic field. In this approach, the divergence difficulty is overcome with a special limit of the derivative of the thermodynamic potential with respect to the magnetic field. The formalism satisfies the particle-hole symmetry of the Dirac fermions system. We apply the formalism to the interact...