An experiment was conducted recently at the RIKEN Nishina Center to determine the \(\beta \) -decay half-lives and \(\beta \) -delayed neutron emission probabilities of neutron-rich Pm, Sm, Eu and Gd nuclei. In this study, we calculate the \(\beta \) -decay properties of the aforementioned neutron-rich isotopes and other nuclei. All nuclei considered in this investigation have mass number \(A > 155\) . Compared with the previous calculations, the current results are in better agreement with the measured data. Our model calculations successfully reproduced 100% (71%) of the measured half-lives within a factor of 10 (2). Furthermore, the calculated neutron emission probabilities show good agreement with the measured data. Specifically, our model calculations reproduced 75% of the measured values within a factor of 10. We present the first-ever microscopic calculation of stellar rates for these heavy and neutron-rich exotic nuclei. The stellar rates were found to be significant beyond core densities ( \(10^{7}\) g cm \(^{-3}\) ) or at high core temperatures ( \(\sim \!\! 30\) GK) prevailing in the stellar core. The reported weak rates may prove useful for the r-process nucleosynthesis calculations.
