The concept of "nuclear compressibility under deformation", introduced by Fradkin and others in their experimental studies of isotope shifts, is analyzed. It is shown that in the harmonic-oscillator model Fradkin's compressibility parameter ξ can occur in a natural way. Theoretical estimates of ξ are obtained, using spherical and deformed oscillator models, as ξ = −5/4π and −5/16π respectively. They bracket the experimental value [Formula: see text]. Possible improvements of these estimates are discussed.
Coherent States and Quantum Numbers for Twist-deformed Oscillator Model
