Dirac Electron in Organic Conductor α-(BEDT-TTF)2I3 with Inversion Symmetry

Diffraction data at ambient pressure and room temperature for the organic conductor alpha-(BEDT-TTF)(2)I-3 have shown the existence of an inversion symmetry between the molecular sites A and A'. This property allows to classify energy bands at the time reversal points G/2 according to their parity (even/odd) under inversion. Using Fu-Kane's argument we can then deduce the existence of Dirac electrons between valence and conduction bands by determining the sign of the parity product over all occupied levels and all time reversal points. The change in the sign of this parity product is related to the merging of Dirac points at one of the time reversal points. Using this property, we can establish clear conditions for the existence of Dirac electrons in alpha-(BEDT-TTF)(2)I-3.