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In quantum mechanics, and in particular quantum chemistry, the electronic density is a measure of the probability of an electron occupying an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typically denoted as either ''ρ''(r) or ''n''(r). The density is determined, through definition, by the normalized ''N''-electron wavefunction which itself depends upon 4''N'' variables (3''N'' spatial and ''N'' spin coordinates). Conversely, the density determines the wave function modulo a phase factor, providing the formal foundation of density functional theory. == Definition == The electronic density corresponding to a normalized ''N''-electron wavefunction (with r and ''s'' denoting spatial and spin variables respectively) is defined as : where the operator corresponding to the density observable is : In Hartree–Fock and density functional theories the wave function is typically represented as a single Slater determinant constructed from ''N'' orbitals, ''φ''''k'', with corresponding occupations ''n''''k''. In these situations the density simplifies to : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「electronic density」の詳細全文を読む スポンサード リンク
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