We encountered several problems with the MPI version of VASP.4.X on the CRAY J90. First MPI_double_precision (MPI_double_complex) must be changed to MPI_real (MPI_complex). Second the reading of the INCAR file must be serialised (i.e. only one node can do the reading at a time). Defining CRAY_MPP in the makefile fixes these problems. But we are not yet sure whether this flag is required on all CRAY MPP machines or not. Any information on that would be appriciated.