Exchange Interactions in a Low-Dimensional Magnetic System Cu(H2O)2(en)SO4

We report a theoretical ab-initio investigation of the exchange interaction between Cu atoms in Cu(H2O)(2)(en)SO4, en=C2H8N2(ethylenediamine), an insulating magnetic material. Unlike previous experimental studies which describe the system as a quasi-two-dimensional antiferromagnet, our results, based on the mapping of the system onto an effective Heisenberg model, suggest a quasi-one-dimensional character of magnetism, with the exchange coupling between the Cu atoms being propagated along a zigzag line, lying in the crystal's be plane and connecting the Cu atoms through the N atoms. Furthermore, we report the calculated positions of the H atoms that have not been provided in experimental papers.