Density-functional based tight-binding calculations on thiophene polymorphism

In this work we present the results of density-functional based tight-binding (DFTB) calculations on the inter-molecular interaction of the following thiophene crystals: /spl beta/-tetramethyl-quaterthiophene (TM4T), monoclinic and triclinic /spl beta/-tetra(methylsulphanyl)-quaterthiophene (TMS4T), and monoclinic and triclinic /spl beta/-tetramethyl-sexithiophene (TM6T).