Fast Experiments for Charge-Density Determination: Topological Analysis and Electrostatic Potential of the Amino Acids $\mathrm{_L-Asn, _{DL}-Glu, _{DL}-Ser}$, and $\mathrm{_L-Thr}$

Synchrotron radiation and CCD detection give the possibility for fast diffraction experiments, which were employed to deduce the exact charge-density distributions of some amino acids. Their topological analysis (the figure shows the negative Laplacian function of dl-serine in the plane of the carboxylate group) yields not only comparable information about intramolecular but also about weak intermolecular interactions