Using Hartree–Fock (HF) and ِِDensity Functional Theory (DFT) calculations the thermodynamic properties such as thermal energy , , thermal enthalpy , , thermal entropy , , thermal Gibbs free energy , , heat capacity ,Cv, and molecular structures of several species involving in keto↔enol tautomerism related to acetaldehyde (A), 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and  acetylacetone (AA) h...

A DFT-SOFM-RBFNN method is proposed to improve the accuracy of DFT calculations on Y-NO (Y = C, N, O, S) homolysis bond dissociation energies (BDE) by combining density functional theory (DFT) and artificial intelligence/machine learning methods, which consist of self-organizing feature mapping neural networks (SOFMNN) and radial basis function neural networks (RBFNN). A descriptor refinement s...

The publication by Cooley and Tukey [5] in 1965 of an e cient algorithm for the calculation of the DFT was a major turning point in the development of digital signal processing. During the ve or so years that followed, various extensions and modi cations were made to the original algorithm [6]. By the early 1970's the practical programs were basically in the form used today. The standard develo...

A new method for calculating optical absorption spectra within linear-scaling density functional theory (LSDFT) is presented, incorporating a scheme for optimizing a set of localized orbitals to accurately represent unoccupied Kohn-Sham states. Three different schemes are compared and the most promising of these, based on the use of a projection operator, has been implemented in a fully functio...

In recent generalized Kohn-Sham (GKS) schemes for density functional theory (DFT) HartreeFock type exchange is important. In plane waves and grid approaches the high cost of exchange energy calculations makes these GKS considerably more expensive than Kohn-Sham DFT calculations. We develop a stochastic approach for speeding up the calculation of exchange for large systems. We show that stochast...

The positions o f continuous diffuse scattering streaks in electron diffraction patterns from oblique layer crystals isostructura 1 to monoclinic paraffins are predicted using the kinematical difference Fourier transform (DFT) model of Amoros and Amoros. However, indications of correlated chain m otions are found as was seen in a bimolecular rectangular layer structure. This correlated chain “ ...

In this study we investigate the effect of atoms such as B, N, Ge and Sn on the optical and the electrical properties of capped (5, 0) zigzag carbon nanotube, using DFT calculation method. These elements were attached to the one end of the carbon nanotube. We considered four different structure designs as possible candidates for a p-n junction device. The electrical properties of these structur...

We show how to describe the coupling of electrons to nonuniform magnetic fields in the framework of the widely used norm-conserving pseudopotential approximation for electronic structure calculations. Our derivation applies to magnetic fields that are smooth on the scale of the core region. The method is validated by application to the calculation of the magnetic susceptibility of molecules wit...

We have applied nuclear inelastic scattering (NIS) and computational predictions based on density functional theory (DFT) to explore the vibrational dynamics of Fe in a trinuclear oxo-bridged iron(III) complex. Quantitative comparison of the experimentally measured vibrational dynamics of the Mössbauer nuclei Fe, with normal mode analysis, calculated via quantum chemical calculation based on DF...

MCSCF-MRMP2 and DFT calculations were performed in order to analyze the stability and geometrical parameters of some possible intermediates for the reactions Ru2+ + H2O2 and Ru(H2O)6 + H2O2. At MCSCF-MRMP2 level of calculation, the stability predicted for the RuO(H2O)5 suggests an energetic preference of the reaction Ru(H2O)6 + H2O2 toward the products involving this high-valence intermediate, ...