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Quantum Methods (quantum + methods)
Selected AbstractsAn improvement of quantum parametric methods by using SGSA parameterization technique and new elementary parametric functionalsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2010M. Sánchez Abstract A systematic improvement of parametric quantum methods (PQM) is performed by considering: (a) a new application of parameterization procedure to PQMs and (b) novel parametric functionals based on properties of elementary parametric functionals (EPF) [Ruette et al., Int J Quantum Chem 2008, 108, 1831]. Parameterization was carried out by using the simplified generalized simulated annealing (SGSA) method in the CATIVIC program. This code has been parallelized and comparison with MOPAC/2007 (PM6) and MINDO/SR was performed for a set of molecules with CC, CH, and HH bonds. Results showed better accuracy than MINDO/SR and MOPAC-2007 for a selected trial set of molecules. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Improvements of parametric quantum methods with new elementary parametric functionalsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2008Fernando Ruette Abstract A series of elementary parametric functionals (EPFs) for resonance integral, electron-electron repulsion, electron-nucleus attraction, core-core interaction, and bond correlation correction were included in the new version of CATIVIC method [Int J Quantum Chem 2004, 96, 321]. In the present work, a systematic way to improve the precision of parametric quantum methods (PQMs) by using several EPFs in the parameterization of a set of molecules is proposed. Based on the fact that a linear combination of elementary functionals from the exact Hamiltonian is also a functional, a linear combination of EPFs has been proved that can enhance the accuracy of PQMs by considering the convex condition. A general formulation of simulation techniques for molecular properties is presented and a formal extension of the minimax principle to PQMs is also considered. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source] Analysis of interaction modes in calix[4]arene,levofloxacin complexes by quantum methodsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 3 2006Alexandrine Lambert Abstract Host,guest interactions between chiral calix[4]arenes and the antibiotic levofloxacin are analyzed on the basis of quantum mechanical calculations at the density functional (for model systems) and semi-empirical levels. The calix[4]arene macrocycle carries two (+)-isomenthyl groups attached to opposing phenyl groups at the lower rim and different substituents (R,=,H, CH3, tBu, CH2CHCH2, COCH3 and NO2) are considered at the upper rim. Nitro derivatives are expected to form ionized complexes whereas the other derivatives should form neutral complexes with a very low stability. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||