Multi-dimensional fission barriers for heavy and superheavy nuclei

Recent macroscopic-microscopic studies of the heights of ( static) fission barriers B-f(st) of the heaviest nuclei are reviewed. The studies are motivated by the importance of this quantity in calculation of cross-sections for synthesis of these nuclei. Large deformation spaces, including as high multipolarities of deformation as lambda = 8, are used for the analysis of B-f(st). The importance of non-axial shapes in this analysis is shown. They reduce B-f(st) by up to about 2MeV. The origin of this large reduction is explained. This is a large ( negative) shell correction to the energy, which overcomes a significant stiffness of the macroscopic part of this energy to non-axial deformations of a nucleus.