Tests of the random phase approximation for transition strengths

Ionel Stetcu, Calvin W. Johnson
2003 Physical Review C  
We investigate the reliability of transition strengths computed in the random-phase approximation (RPA), comparing with exact results from diagonalization in full $0\hbar\omega$ shell-model spaces. The RPA and shell-model results are in reasonable agreement for most transitions; however some very low-lying collective transitions, such as isoscalar quadrupole, are in serious disagreement. We suggest the failure lies with incomplete restoration of broken symmetries in the RPA. Furthermore we
more » ... Furthermore we prove, analytically and numerically, that standard statements regarding the energy-weighted sum rule in the RPA do not hold if an exact symmetry is broken.
doi:10.1103/physrevc.67.044315 fatcat:ytjmn7xworeutp4wvjsvs7mgyi