The so called "isobar run" or RHIC was designed to compare a number of observables for collisions of 96 40 Zr with those of 96 44 Ru, aimed at identification of Z-dependent effects. However, the STAR data have shown, with unprecedented accuracy, that these two nuclides have properties which differ stronger than expected, and multiple studies tried to quantify their shape differences, in relation to various observables. General consensus is that it somehow should be related to nuclear structure calculations, for the ground and lowest excited states. Yet the precise connection between these fields -low and high energy nuclear physics -is still missing. In this paper I propose such a connection, via a concept of thermal density matrices of a "preheated" nuclei.