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Oneelectron equations for embedded electron density: challenge for theory and practical payoffs in multilevel modeling of complex polyatomic systems 

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Published in  Leszczynski, Jerzy. Computational chemistry : reviews of current trends, Vol. 10: World Scientific. 2006, p. 82  
Abstract  The idea of describing a manyelectron system using only its electron density, i.e. without constructing its wavefunction, was initiated in the works of Thomas and Fermi. HohenbergKohn theorems of modern density functional theory transformed this idea into an exact theory. The KohnSham formalism, widely used in computer simulations of polyatomic systems today, is based on these theorems but is not orbitalfree. It reintroduces orbitals to minimize errors in approximating the total energy. The present review concerns an alternative formalism based also on HohenbergKohn theorems, in which orthogonal orbitals are used not for the whole system but only for subsystems [Cortona, Phys. Rev. B, 44 (1991) 8454]. These orbitals are derived from KohnShamlike oneelectron equations, called here KohnSham Equations with Constrained Electron Density (KSCED), in which all terms representing the interactions between the subsystems are expressed as universal functionals of electron density. This formulation provides the formal basis for the orbitalfree embedding in firstprinciples based multilevel simulations of complex systems, in which the orbitallevel is retained for a selected subsystem, whereas its environment is described at the orbitalfree level [Wesolowski and Warshel, J. Phys. Chem., 97 (1993) 8050]. The formal aspects, development and testing of relevant approximate density functionals, and the possible use of the orbitalfree embedding in multilevel modelling are covered in detail in this review. Examples of applications, especially those concerning the electronic structure of embedded systems in the condensed phase are provided.  
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Citation (ISO format)  WESOLOWSKI, Tomasz Adam. Oneelectron equations for embedded electron density: challenge for theory and practical payoffs in multilevel modeling of complex polyatomic systems. In: Leszczynski, Jerzy (Ed.). Computational chemistry : reviews of current trends, Vol. 10. [s.l.] : World Scientific, 2006. p. 82. https://archiveouverte.unige.ch/unige:4036 