                                               Scalar external_virial_xz,
                                               Scalar external_virial_yy,
                                               Scalar external_virial_yz,
-                                              Scalar external_virial_zz)
+                                              Scalar external_virial_zz,
+                                              bool twod)
     {
     Scalar final_sum[6];
 

                                                                               args.external_virial_xz,
                                                                               args.external_virial_yy,
                                                                               args.external_virial_yz,
                                                                               args.external_virial_zz
                                                                               );
        }


        // fill out the GPUArray
        // we have thus far calculated the sum of the kinetic part of the pressure tensor
        // and the virial part, the definition includes an inverse factor of the box volume
        Scalar V = box.getVolume(twod);

        d_properties[thermo_index::pressure_xx] = final_sum[0]/V;
        d_properties[thermo_index::pressure_xy] = final_sum[1]/V;
