PRESSURE-DEPENDENCE OF THE STRUCTURAL AND ELECTRONIC-PROPERTIES OF THE MOLECULAR SUPERCONDUCTOR, (BEDT-TTF)2CU(NCS)2

We report the compressibility tensor calculated from the pressure dependence (< 13kbar) of the cell parameters and the structural and electronic properties derived from the high pressure (7.5kbar) crystal structure of the title compound. The magnitudes of the principal compressibilities k1 decreases very slightly and the bulk modulus strongly increases with increasing pressure. k2 is along the crystallographic b axis. Thus, the directions of the smallest(k3) and largest (k1) are in the ac plane; on the projection along the b axis, k3 is parallel to the long axis of the molecule and corresponds to the maximum density of atoms. The crystal structure of a twinned crystal has been refined to R = 0.095. Using the atomic coordinates, the transfer integrals have been calculated; the comparison of the high and ambient pressure band structures shows that the two-dimensional character of this compound is enhanced by pressure.