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...

Theoretical studies have been carried out on bio active molecules such as Naphthalene (npa) and its derivatives naphthalene-2-sulfonic acid (nsa) 1-nitroso-2-naphthol (nnol) using both Ab initio HF DFT-B3LYP methods with 6-311++G(d,2p) basis sets. The geometrical parameters, molecular properties vibrational spectra of nsa, nnol npa were calculated analyzed. Geometrical optimizations the done by...

The electron-hole explicitly correlated Hartree-Fock method (eh-XCHF) is presented as a general strategy for investigation of electron-hole correlation and computation of electron-hole recombination probability. The eh-XCHF method is a variational method which uses explicitly correlated wavefunction that depends on the electron-hole inter-particle distances. It is shown that the explicitly corr...

The effect of electron-correlation on the ground-state properties of CeN and LaN is studied by ab initio quantum-chemical methods. The approach which is used combines two separate steps: (1) the ground-state Hartree-Fock calculations for the crystal; (2) application of the method of increments to the studied system, which allows an expansion of bulk properties using the information from quantum...

New relativistic energy-consistent pseudopotentials have been generated for the 5d transition metals Hf-Pt. The adjustment was done in numerical two-component multiconfiguration Hartree-Fock calculations, using atomic valence-energy spectra from four-component multiconfiguration Dirac-Hartree-Fock calculations as reference data. The resulting two-component pseudopotentials replace the [Kr]4d(10...

This paper presents symmetry classes of the Hartree-Fock (HF) solutions of spin and orbital ordered states in a t2g Hubbard model on a two-dimensional square lattice. Using a group theoretical bifurcation theory of the Hartree-Fock equation, we obtained many types of broken symmetry solutions which bifurcate from the normal state through one step transition in cases of commensurate ordering vec...

Measurements of secondand third-order nonlinear polarizabilities (hyperpolarizabilities) for HF and HCI using dc electric-field-induced secondharmonic generation are presented: xt(HF) = 70(10) X 10esu/mol, xl() (HF) = 4.70(41) X 10esu/mol, XIl )(HCI) = 347(15)X 10esu/mol, Xlf)(HCI) = 4.22(50) X 10esu/mol. In the case of HF this allows a critical comparison with theory. HF has fewer electrons th...

We describe the new version 2.00c of the code hfbtho that solves the nuclear Skyrme Hartree-Fock (HF) or Skyrme Hartree-Fock-Bogolyubov (HFB) problem by using the cylindrical transformed deformed harmonic-oscillator basis. In the new version, we have implemented the following features: (i) the modified Broyden method for non-linear problems, (ii) optional breaking of reflection symmetry, (iii) ...