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METHOD FUNKTSIONALA OF DENSITY

The methods based on the theory funktsionala of density (density functional theory, DFT) [71, 74, 75], for present time are most vostrebovannyyomi as results of their application make a worthy competition anayologichnym to the data received at use of "traditional" methods of quantum chemistry [80].

The theory funktsionala to density was preceded by Thomas-Fermi's model (1927), based on the assumption of equality of occupied volumes for all electrons in phase space (each elementary volume two electrons occupy). Absence of the account of exchange interaction between electrons and energy of electronic correlation Nevertheless was the main lack of model, she allowed to calculate energy of separate atom, representing it in the form of the sum of its drop energy expressed through funktsional by the electronic
Density, and potential energy of interaction of electrons with each other and with a kernel, also presented to a kind funktsionala electronic density. Specification funktsionala energy by means of the summand describing obmenyonoe interaction, was offered Field Dirakom (1928г). However and this obyoedinyonnaja Thomas-Fermi-Diraka model yielded an error in calculations obyomennoj to energy and neglected energy of electronic correlation.

The reliable theoretical substantiation of the theory funktsionala has been yielded density by Pierre Hoenbergom and Uolterom the Game in two theorems (1964). The first theorem considers electrons in external potential of nuclear kernels and utveryozhdaet, that between density of the basic condition of electrons and potential of kernels there is the mutual unequivocal conformity. However this position does not yield methods of construction of such conformity. The second theorem postulates, that if energy of an electronic subsystem is written down in a kind funktsionala electronic density its minimum is equal to energy of the basic condition. Thus, energy is funktsional electronic density [74, 77]:

At the description of electronic system multielectronic wave function in a method funktsionala density is replaced with electronic density, which javyoljaetsja function only three dimensional co-ordinates. The formalism of Game - SHema in this method has reduced a problem about the quantity description vzaimodejyostvujushchih electrons in external potential of kernels to more simple problem about neyozavisimyh electrons, moving in some effective potential (stayotichesky potential of nuclear kernels, exchange interaction and electronic koryoreljatsija) [81]. Multielectronic wave function of connection is connected with elekyotronnoj in density of the basic condition r (). But as electrons nerazliyochimy, r () there is a centre density on system Nэлектронов [71, 74, 75]. In one determinant approach function of electronic density of the core soyostojanija represents the sum of density nuclear orbitalej:

Descriptions of exchange and correlation interaction have been specified and expanded already in the early nineties [82-84]. From now on the method funktsionala density is the basic computing kvantovo-chemical approach. Including for calculation of energy of ionisation of atom. Electron affinity. elekyotrootritsatelnosti. Electronic energy etc. [85-86].

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A source: Rusakova Natalia Petrovna. QUANTUM-CHEMICAL STUDY OF THE ELECTRONIC STRUCTURE OF SERO-CONTAINING MOLECULES AND RADICALS. DISSERTATION for the degree of Candidate of Chemical Sciences. Tver - 2015. 2015

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