Values of the lattice constants of tetramethyltetraselenafulvalene hexafluorophosphate at 3 kbar (room temperature) have been measured by x-ray methods and compressibilities have been determined. The needle direction ($a$ axis) is reduced by approximately 0.5%/kbar while the normal directions are an order of magnitude less compressible.

• Received 22 April 1982

DOI:https://doi.org/10.1103/PhysRevB.26.2660