A spin-1/2 Heisenberg model on a honeycomb lattice is investigated by doing triplon analysis and quantum Monte Carlo calculations. This model, inspired ${\mathrm{Cu}}_{2}{(\mathrm{pymca})}_{3}({\mathrm{ClO}}_{4}$), has three different antiferromagnetic exchange interactions (${J}_{A}, {J}_{B}, {J}_{C}$) sets of nearest-neighbor bonds which form kagome superlattice. While the bipartite unfrustra...

We have measured the magnetic susceptibility of the ironsulfur proteins, ferredoxin from both spinach and parsley, and high potential protein from Chromafium in the oxidized and reduced state. Over the temperature range 1.4-201” K the oxidized plant proteins are either totally diamagnetic or exhibit trace paramagnetism. The reduced proteins are strongly pararnagnetic with a susceptibility appro...