Simple correlations between electric quadrupole moments of atomic nuclei ...

Measurements of non-yrast electric quadrupole moments (i.e., diagonal E2 matrix elements)
of atomic nuclei are becoming widely available from multiple-step Coulomb excitation. It is shown that, where quadrupole-moment data exist, $\langle 2_1^+ ||E2|| 2_1^+ \rangle+\langle 2_2^+ ||E2|| 2_2^+ \rangle\approx 0$ is observed across a wide range of masses and deformations. In addition, $\langle 4_1^+ ||E2|| 4_1^+ \rangle+\langle 4_2^+ ||E2|| 4_2^+ \rangle+\langle 4_3^+ ||E2|| 4_3^+ \rangle\approx 0$ is observed within two standard deviations for three of the four existing measurements. Rotor models appear to be sufficient in describing these trends.