Inside Cover, Volume 113, Issue 12

In a fashion similar to how the periodic table is used to characterize elements, a set of variables can be used to characterize chemical compounds and determine their quantum mechanical properties. For each element in the periodic table, all possible stoichiometries are displayed that can be obtained by repartitioning onto multiple atomic sites with variable atomic numbers, nuclear charges, and the N p protons that make up the atomic number. As presented by O. Anatole von Lilienfeld on page 1676 , the cover image exemplifies the case of N p = 10 protons. Here, N I , Z I , and i are number of atoms in a given compound, nuclear charge of atom I, and stoichiometry index (sorted by increasing N I ), respectively. Thus, each column corresponds to a different stoichiometry, various familiar compositions are pointed out, and in the limit of N I →1 the stoichiometry corresponds to Ne, while H 10 is recovered for N I → N p