Compressed nuclei in a schematic relativistic mean-field description

The relativistic mean-field approximation is extended to compressed nuclei by adding a constraint to the Lagrangian that models an external pressure. For a constraint depending on the meson fields we calculate total energies, intrinsic nuclear energies, single-particle energies, and densities of compressed nuclei. At some critical compression remarkable changes of the nuclear structure are found resembling phase transitions. These changes are connected with discontinuities in the single-particle structure caused by compression.