2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/175627The long-standing problem of dramatic structure change near N=40 in Ge isotopes is investigated by means of large-scale shell model calculation. The analysis of simulated calculations suggests a possible understanding of the problem in terms of rapid increase in the $g_{9/2}$ proton and neutron occupation. The observed variation in excitation of the second $0^+$ state in $^{70,72,74}$Ge appears to correlate closely with the $g_{9/2}$ occupations induced by strong proton-neutron interactions. The enhancement of the $g_{9/2}$ occupancies is probably due to correlations in the $1g2d3s$ shell.11 pages, 5 figures, accepted for publication in Nuclear Physics ANuclear Theorytext