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Figure 12
Theoretical vector fields of the gradients of the ED ∇ρ(r) (black), the electrostatic potential ∇φes(r) (blue) and the kinetic potential ∇φk(r) (orange) of the free hydrogen-bonded, π-stacked dimer of 1,3-bis­(2-hy­droxy­ethyl)-6-methyl­pyrimidine-2,4(1H,3H)-dione, representing the uracil–uracil interaction. Zero-flux surfaces are highlighted with thicker lines of the corresponding color. The fields are shown as trajectories and overlaid in the planes of the N1′, N3′ and O4 atoms. Saddle CPs (3, −1) in ρ(r), φes(r) and φk(r) are indicated by magenta and violet rhombuses and green squares, respectively. Gradient lines starting from these CPs and ending at the nuclei are colored red, violet and green, respectively. An out-of-plane distance is set to 0.5 a.u. The distance between the axis tick marks is 1 Å.

IUCrJ
Volume 10| Part 5| September 2023| Pages 584-602
ISSN: 2052-2525
https://doi.org/10.1107/S2052252523007108