英语翻译Natural Bond Orbitals (NBOs) are localized few-center or

英语翻译
Natural Bond Orbitals (NBOs) are localized few-center orbitals ("few" meaning typically 1 or 2,but occasionally more) that describe the Lewis-like molecular bonding pattern of electron pairs (or of individual electrons in the open-shell case) in optimally compact form.More precisely,NBOs are an orthonormal set of localized "maximum occupancy" orbitals whose leading N/2 members (or N members in the open-shell case) give the most accurate possible Lewis-like description of the total N-electron density.
Neither the form of the bonding hybrids nor the locations of localized bonds and lone pairs are pre-determined.Rather,the NBO program searches over all possible ways of drawing the bonds and lone pairs for the variationally optimal bonding pattern that places maximum occupancy (highest percentage of the total electron density) in the leading N/2 "Lewis-type" NBOs (typically >99.9% for common organic molecules).The Lewis-type NBOs determine the localized Natural Lewis Structure (NLS) representation of the wavefunction,while the remaining "non-Lewis"-type NBOs complete the span of the basis and describe the residual "delocalization effects" (i.e.,departures from a single localized Lewis structure).Thus,NBOs provide a valence bond-type description of the wavefunction,closely linked to classical Lewis structure concepts.As in the NAO case,the only input to the NBO algorithms is the molecular wavefunction Ψ (through its first-order reduced density operator Γ),so the numerically determined Lewis structure representation is "natural" to Ψ itself.