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SCF Method (scf + method)
Selected AbstractsAnalysis of self-interaction correction for describing core excited statesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2007Yutaka Imamura Abstract Core-excitation energies are calculated by the self-interaction-corrected time-dependent density functional theory (SIC-TDDFT) and SIC-delta-self-consistent field (SIC-,SCF) methods. For carbon monoxide, SIC-TDDFT severely overestimates core-excitation energies, while the SIC-,SCF method using Kohn,Sham density functional theory (KS-DFT) slightly overestimates. These behaviors are attributed to the fact that the self-interaction errors in the total and orbital energies considerably differ. We evaluate the difference of the self-interaction errors for the Slater exchange functional. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Toward a BSSE-free description of strongly interacting systemsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2002G.J. Halász Abstract The so-called "chemical Hamiltonian approach" (CHA) gives perfect a priori BSSE-free description of weak intermolecular interactions, but has been found inappropriate for describing strong interactions taking place within a molecule. Here, we propose a simple modification of the CHA/F BSSE-free SCF method, which retains all the good properties of the CHA/F method for the intermolecular case but can be used also to describe covalent and ionic interactions. This is vital for calculating whole potential surfaces of chemical reactions in a consistent manner, which was found impossible by using the a posteriori counterpoise correction method. Model calculations are presented for covalent and ionic chemical bonds and for a rare gas,proton system. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source] Improvement of insulin absorption from intratracheally administrated dry powder prepared by supercritical carbon dioxide processJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2003Hiroaki Todo Abstract The purpose of this study was to improve insulin absorption from dry powder after administration in lung without an absorption enhancer. The dry powders, with mannitol as a carrier, were prepared with or without an absorption enhancer (citric acid) by supercritical carbon dioxide (SCF) and spray drying (SD) processes. Insulin powder was precipitated from dimethyl sulfoxide and aqueous solutions by dispersing the insulin solutions from parallel and V-type nozzles, respectively, into supercritical carbon dioxide, which is an antisolvent for insulin. In vitro aerosol performance was evaluated with a cascade impactor. Insulin powder containing citric acid prepared by the SCF method (MIC SCF) showed improved inhalation performance compared with insulin powder prepared by the SD process, although the particle size of the former powder was larger than that in powders prepared by SD. Insulin absorption was estimated from the change in plasma glucose level. The blood glucose level after administration of the insulin powder without citric acid prepared by the SCF process (MI SCF) decreased rapidly, and a significant difference was observed for areas under the curve of change in plasma glucose concentration versus time (AUCs) between MI SCF and the insulin powder without citric acid prepared by the SD process (MI SD). These results suggest that the SCF technique would be useful to prepare dry powders suitable for inhalation. © 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:2475,2486, 2003 [source] Appropriate SCF basis sets for orbital studies of galaxies and a ,quantum-mechanical' method to compute themMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008Constantinos Kalapotharakos ABSTRACT We address the question of an appropriate choice of basis functions for the self-consistent field (SCF) method of simulation of the N -body problem. Our criterion is based on a comparison of the orbits found in N -body realizations of analytical potential,density models of triaxial galaxies, in which the potential is fitted by the SCF method using a variety of basis sets, with those of the original models. Our tests refer to maximally triaxial Dehnen ,-models for values of , in the range 0 ,,, 1, i.e. from the harmonic core up to the weak cusp limit. When an N -body realization of a model is fitted by the SCF method, the choice of radial basis functions affects significantly the way the potential, forces or derivatives of the forces are reproduced, especially in the central regions of the system. We find that this results in serious discrepancies in the relative amounts of chaotic versus regular orbits, or in the distributions of the Lyapunov characteristic exponents, as found by different basis sets. Numerical tests include the Clutton-Brock and the Hernquist,Ostriker basis sets, as well as a family of numerical basis sets which are ,close' to the Hernquist,Ostriker basis set (according to a given definition of distance in the space of basis functions). The family of numerical basis sets is parametrized in terms of a quantity , which appears in the kernel functions of the Sturm,Liouville equation defining each basis set. The Hernquist,Ostriker basis set is the ,= 0 member of the family. We demonstrate that grid solutions of the Sturm,Liouville equation yielding numerical basis sets introduce large errors in the variational equations of motion. We propose a quantum-mechanical method of solution of the Sturm,Liouville equation which overcomes these errors. We finally give criteria for a choice of optimal value of , and calculate the latter as a function of the value of ,, i.e. of the power-law exponent of the radial density profile at the central regions of the galaxy. [source] | ||||||||||