We present and discuss the results of calculations of the CaF2 bulk and surface electronic structure. These are based on the ab initio Hartree–Fock (HF) method with electron correlation corrections and on Density Functional Theory (DFT) calculations with different exchange-correlation functionals, including hybrid exchange techniques. Both approaches use the localised Gaussian-type basis set. A...

We aim to describe nuclear collective excitations starting from correlated realistic nucleon-nucleon (NN) interactions. The latter are constructed within the Unitary Correlation Operator Method (UCOM) [1, 2], which explicitly considers short-range correlations in order to properly soften the short-range behaviour of realistic NN potentials. It has been concluded that first-order RPA with a two-...

Following a previous paper on the 3d series, specific-mass isotope shifts are computed, by means of the non-relativistic Hartree-Fock method, in atoms of the 4d, 4f, 5d and 5f series, in the alkalis and in a few twoand three-electron spectra. In heavy atoms, when isotopic measurements of muonic X-ray transition lines are available, direct comparisons with experiment are presented for optical tr...

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 study isoscalar (IS) and isovector (IV) densities in ${}^{40} \mathrm{Ca}$ comparison with theoretical calculated by Skyrme Hartree-Fock (HF) models. The charge symmetry breaking the independence forces are introduced to effect on IV density. of isospin mixing ground-state density is examined using particle-vibration coupling model taking into account collective giant monopole excitation. sh...

Computational studies on three tautomeric forms of four 1,5,6,7-tetrahydro- 4H-indazol-4-one derivatives: 1,5,6,7-tetrahydro-4H-indazol-4-one (1), 6,6-dimethyl- 1,5,6,7-tetrahydro-4H-indazol-4-one (2), 3-methyl-1,5,6,7-tetrahydro-4H-indazol-4-one (3) and 3,6,6-trimethyl-1,5,6,7-tetrahydro-4H-indazol-4-one (4), have been performed at different levels, ranging from semiempirical AM1, ab initio Ha...

By using three different hybrid exchange-correlation functionals containing 20%, 35%, and 50% of exact Hartree-Fock (HF) exchange of the density functional theory and its time-dependent extension plus the Hartree-Fock and the configuration interaction of single excitation methods, equilibrium geometries, and their 30 vibrational-normal-mode frequencies of the ground S(0)((1)A(1)) and the first ...

The effective fragment potential (EFP) method for treating solvent effects provides relative energies and structures that are in excellent agreement with the analogous fully quantum [i.e., Hartree-Fock (HF), density functional theory (DFT), and second order perturbation theory (MP2)] results for small water clusters. The ability of the method to predict bulk water properties with a comparable a...

We have measured the local electronic compressibility of a two-dimensional hole gas as it crosses the B = 0 metal-insulator transition. In the metallic phase, the compressibility follows the mean-field Hartree-Fock (HF) theory and is found to be spatially homogeneous. In the insulating phase it deviates by more than an order of magnitude from the HF predictions and is spatially inhomogeneous. T...

Exciton effects on soliton and bipolaron lattice states are investigated using an electron-lattice Peierls model with long-range Coulomb interactions. The Hartree-Fock (HF) approximation and the single-excitation configurationinteraction (single-CI) method are used to obtain optical absorption spectra. We discuss the following properties: (1) The attraction between the excited electron and the ...