Quantum crystallographic charge density of urea

Wall, M.E.

doi:10.1107/S2052252516006242

Figure 4
Displacement ellipsoids at 50% probability for (a) Quantum-S, (b) Quantum-M, and (c) neutron diffraction models. In each structure, the O atom is red, the C dark grey, the N blue, and the H1 and H2 light grey, with the H2 at the bottom of the molecule. The Quantum-N model is not shown as it is indistinguishable from the Quantum-M model; similarly, the multipole model is not shown as it is indistinguishable from the neutron. The latter is due to the fact that the hydrogen parameters of the multipole model were copied from the neutron model (Birkedal et al., 2004