Some predicted relationships and properties for the charge distribution in crambin

An HF/3-21G calculation was performed for crambin, which is present in seeds of Crambe abyssinica, at the recent 0.54 Å−1 resolution X-ray geometry. The resulting electron distribution function was analyzed using Bader’s topological method. The density at bond critical points in the peptide unit shows some scatter in the correlation with bond length. Additionally, (3,−3) critical points (local minima) were located in ∇2ρ(r) within the valence shell charge concentration region of the carbonyl oxygen atoms. These points always lie near the plane of the peptide unit, which itself is sometimes not precisely planar.