The Intermolecular Interaction of Tetrathiafulvalene and Bis(ethylenedithio)tetrathiafulvalene in Organic Metals. Calculation of Orbital Overlaps and Models of Energy-band Structures

Abstract

Abstract Based on the extended Hückel molecular orbital calculations, the relation between the anisotropy of the band structure and the arrangement of the organic molecules is investigated for two organic donors, tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT–TTF). The intermolecular overlaps of their HOMO are calculated while the intermolecular arrangements are varied. The maps of the overlaps thus obtained are then used to estimate the band-structure parameters of (TMTTF)2X and (BEDT–TTF)2ClO4(C2H3Cl3)0.5. The Fermi surface of (TMTTF)2X is quasi-one-dimensional and not closed. On the contrary, (BEDT–TTF)2ClO4(C2H3Cl3)0.5 is regarded as a two-dimensional semimetal.