  Nuclear masses ranging from O to Ti isotopes are systematically investigated
with relativistic continuum Hartree-Bogoliubov (RCHB) theory, which can provide
a proper treatment of pairing correlations in the presence of the continuum.
From O to Ti isotopes, there are 402 nuclei predicted to be bound by the
density functional PC-PK1. For the 234 nuclei with mass measured, the root mean
square (rms) deviation is 2.23 MeV. It is found that the proton drip-lines
predicted with various mass models are roughly the same and basically agree
with the observation. The neutron drip-lines predicted, however, are quite
different. Due to the continuum couplings, the neutron drip-line nuclei
predicted are extended further neutron-rich than other mass models. By
comparison with finite-range droplet model (FRDM), the neutron drip-line
nucleus predicted by RCHB theory has respectively 2(O), 10(Ne), 10(Na), 6(Mg),
8(Al), 6(Si), 8(P), 6(S), 14(K), 10(Ca), 10(Sc), and 12(Ti) more neutrons.
