Publications et Ouvrages des Enseignants

Kheira Zineb BOUSMAHA
par Kheira Zineb BOUSMAHA, samedi 9 mai 2020, 22:25
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exercices sur la récursivité

 
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corrigé détaillé de l'exo1 et l'exo2 de la fiche sur la récursivité

 
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Abstract
Feynman–Hibbs corrections in molecular dynamics computer calculations of solid C60 are implemented within the classical effective pair potential approach. The potential model chosen for the site–site interactions is of the Buckingham exp-6 type (Rigby 1986 The Forces Between Molecules (New York: Oxford University Press)), fitted to the Cheng and Klein or the Kitaïgorodsky potential. Structural and thermodynamic properties of the C60 crystal lattice are investigated over a wide range of pressures and temperatures, and data obtained are compared to experimental results and those obtained from a classical approach (Baameur et al 2000 Phys. Status Solidi 220 821). It will be demonstrated that 'quantum corrections' applied in a simple quasi-classical simulations have a great influence upon most calculated properties and increase their accuracy when compared to classical approaches. The observed transition pressure with the distorted lattice and cell contraction compares favourably well with experimental data and equation of state calculations. All measured properties are reported together with the phonon density of states at different pressures.
 
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Abstract
Quantum mechanical studies were carried out in order to understand and describe the nature and strength of the hydrogen bond topology in three dimensional water cluster systems (H2O)n, in the size range 6–20 molecules. Optimal structures and vibrational frequencies of cage like water clusters are computed at the Hartree–Fock (HF) and the electronic density functional theory (DFT) level of theory with a detailed data analysis. Theoretical results are compared to experimental data when available. The general tendency is a decrease of the global minimum energy as the cluster size increases. The nearest neighbour separation between oxygen atoms decreases exponentially when the cluster size increases. The present work suggests that DFT results are in a good agreement with the corresponding HF data, however slight differences remain with regard to values of the nearest neighbour separation between oxygen atoms. The Morokuma’s decomposition of the total interaction energy performed on two and three-dimensional clusters lead to a better understanding of the cluster formation with a strong polarization energy component.
 
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Abstract
The properties of the regular and irregular dodecahedron water clusters (H2O)20, with and without the presence of guest molecules such as N2, CO2, CH4, and C2H6 are calculated at the Hartree–Fock (HF) level of theory with 6-31G(d) basis set. Although the dodecahedron in its regular arrangement is more favourable than the irregular one, embedding a guest molecule in the cavity of the cage structure leads to a different behaviour as far as the calculated data between these two different conformations are concerned. The computed stabilisation energy for each system increases with the presence of the guest molecules in the cavity. The Morokuma’s decomposition of the total interaction energy performed on three dimensional clusters leads to a better understanding of the cluster formation with a strong charge transfer energy component from the host to the guest.
 
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Abstract
The local anaesthetic Tetracain has previously been found to block, induce or potentiate Ca2+ release from
the sarcoplasmic reticulum of skeletal muscle. Cyclodextrins (CD) are complexing agents that have been
successfully used as pharmaceutical drug carriers, to improve the bioavailability of medicines. The aim of this work
is to investigate the inclusion process of the local anesthetic Tetracain with the beta-cyclodextrin at the Hartree–Focklevel
of theory calculations with a 6-31G (d) basis set, and to evaluate stabilization upon the formation of the inclusion
compounds for 1:1 association. The inclusion process pathways are described and the most stable structures
of the different complexes are sought through a global potential energy scan. The data suggest that the most
stable structure for the 1:1 stoichiometry between the Tetracain and the β-CD is obtained when the inclusion
complex formed by Tetracain from the tertiary amine group, entering into the cavity of β-CD from its narrow side
(i.e. the primary 6-CH2OH hydroxyl group). Structure–activity relationship is discussed in terms of different
molecular descriptors and experimental Raman spectroscopy measurements at different mole fraction for
the inclusion complexes analyzed and compared with our theoretical constructed Raman spectra.
 
 
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Abstract
To date, the Wittig reaction remains the most commonly used method in organic chemistry. The synthesis approach yields to a possible functionalization of the olefin product through the transformation of the carbonyl function (ketones or aldehydes) with a phosphoniumylide. In the present work, the two approaches are used to describe the mechanism of the Wittig reaction. Static quantum calculations at the DFT level of theory with a B3LYP functional and 6–31 g(d, p) basis set are carried out and correlated to metadynamics calculations, exploring the free energy landscape of the reaction. The free energy barriers are calculated along the trajectory path, and the mechanism is discussed with the main features observed in the MTD calculations when compared to static quantum investigations. The latter do not allow for the identification of all points that may occur along the reaction path. Static quantum calculation converges to limited geometry states, while the metadynamics converges to several metastable and stable geometries and configurations. Moreover, the strong dependence of the reaction dynamics upon the functional and pseudopotential used highlights the importance of the dispersion forces along the reaction path. A complete description of the reaction mechanism from both the free energy standpoint and the structural configurations of the molecular species is discussed in detail. The differences in the free energy profile are discussed in terms of the limited account of the dispersion interactions within the DFT approach and the standard local XC functionals, confirming the strong non-covalent interactions and molecular rearrangement of charged species that take place all along the reaction path.
 
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تتناول هذه الدراسة فهرسة لحزانة الشيخ البشير محمودي بدائرة البرج لولاية معسكر، لصاحبها الشيخ البشير بن الحاج قدور محمودي، وهي خزانة قيمة تحوي نفائس المخطوطات في شتى العلوم والفنون، تفوق 500 مخطوط، زارها الكثير من الباحثين أمثال الشيخ المهدي البوعبدلي، الشيخ نعيم النعيمي، كما كانت لنا فرصة زبارتها ومرافقة شيخها، والتزود منها

 
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مخطوط نفيس لأبي راس الناصر وهو شرح على كتاب الروضة السلوانية لعبد الجبار

شرحه ابو راس الناصر المعسكري، وهو شرح نفيس، ضمنه صاحبه أشعارا ومعلومات واشارات تاريخية مهمة جدا.