Density Functional Procedures

Although Eq. (3.1) is an exact formula for the electrostatic potential due to a set of nuclei ZA and an electronic density p(r), the latter [p(r)] is generally obtained computationally from an ab initio or semi-empirical wave function or, more recently, from density functional procedures and is therefore necessarily approximate. It follows that the resulting V(r) is also approximate. 

Chendra, A. K., and A. Goursot. 1996. Calculation of Proton Affinities Using Density Functional Procedures A Critical Study. J. Phys. Chem. 100,11596. 

Gas-phase heats of formation for tetraazapentalene derivatives 13-16 were computed using a density functional procedure. Optimized structures and relative energies were computed for the key molecular framework and several isomeric forms. The unexpected observed tetraazapentalene stability is explained by the relatively positive character of the triply coordinated nitrogens <1995JMT63>. 

The set of molecular orbitals leading to the lowest energy are obtained by a process referred to as a self-consistent-field or SCF procedure. The archetypal SCF procedure is the Hartree-Fock procedure, but SCF methods also include density functional procedures. All SCF procedures lead to equations of the form. 

A density functional procedure has been used to compute the gas-phase heat of formation of the triazolooxadiazole 17, and the calculated value of Ai/f° at 202 kcal moP (903 cal is more than 4 times greater than that of a leading military explosive, l,3,5-trinitrohexahydro-l,3,5-triazine (RDX), 18 (206cal g ), which supports the hypothesis that a high energy content is associated with nitrogen catenation <1995JST(358)63>. 

Density functional techniques are available for the calculation of the molecular and electronic structures of ground state systems. With the functionals available today, these compete with the best ab initio methods. This article focuses on the theoretical aspects associated with the Kohn Sham density functional procedure. While there is much room for improvement, the Kohn-Sham exchange-correlation functional offers a great opportunity for theoretical development without returning to the uniform electron gas approximation. Theoretical work in those areas will contribute significantly to the development of new, highly precise density functional methods. 

In the present paper we show that the experimental behaviour can be well reproduced by stand d theoretical calculations limited to the reactions of the prototype nitrone (H-nitrone), provided that a fairly high level of electron correlation be introduced, either with the Moeller-Plesset perturbation technique or with the use of the Density Functional procedures. 

The phosphane molecule is the subject of numerous quantum-chemical calculations. The methods applied range from simple LCAO MO approaches to high-quality calculations, such as Hartree-Fock (SCF MO), configuration interaction (Cl), perturbation theory (MP, MBPT), and, more recently, density function procedures. 

The relative reaction rates of the 1,3-dipolar cycloaddition reaction of phenyl azide to dipolarophiles containing the C=C bond can be predicted by using the Jaguar V. 3.0 ab initio electronic package. Thermodynamic analysis of the 1,3-dipolar cycloaddition of organic azides with conjugated nitroalkenes at 273-398 K shows that temperature does not affect the course of these reactions in the vapour phase. Density-functional procedures have been used to explain the regioselectivity displayed by the 1,3-dipolar cycloaddition of azides with substituted ethylenes. A density-functional theory study of the 1,3-dipolar cycloaddition of thionitroso compounds with fulminic acid and simple azides indicates that the additions are not stereospeciflc. ... 

Within the past 10 years, density functional procedures " have emerged as an effective alternative to the more traditional ab initio and semiempirical approaches to computing molecular properties. Density functional theory is based on the Hohenberg-Kohn theorem, which states that all of the electronic properties of a chemical system, including the energy, are determined by the electronic density, The resulting... 

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