Toward crystal design in organic conductors and superconductors

摘要

We have seen that many different types of intermolecular interactions in organic211u001econducting cation radical salts. Hydrogen bonding between the donor molecules and 211u001ethe anions is weak but not negligible. The ionic Madelung energy is insufficient 211u001eto completely intersperse anions and cations, thus the layers favored by the van 211u001eder Waals interactions remain intact. The search for new conducting and 211u001esuperconducting salts has been mainly by trial-and-error methods, even though 211u001esimple substitutions have been employed in order to obtain isostructural analogs 211u001eof successful (e.g., superconducting) salts. However, even seemingly minor 211u001esubstitutions sometimes destroy the packing type, and different crystal 211u001estructures result. Simulations with the aim at predicting crystal structures have 211u001enot succeeded, mainly because the different interaction types are of comparable 211u001eenergy, and the delocalized and partial charges render the calculations of the 211u001eionic terms extremely unreliable. Clearly, the development of suitable crystal 211u001emodeling techniques with predictive capabilities is one of the great needs of the 211u001efield.