Generator coordinate method calculations for ground and first excited collective states in He-4, O-16 and Ca-40 nuclei

The main characteristics of the ground and, in particular, the first excite d monopole state in the He-4, O-16 and Ca-40 nuclei are studied within the generator coordinate method using Skyrme-type effective forces and three co nstruction potentials, namely the harmonic-oscillator, the square-well and Woods-Saxon potentials. Calculations of density distributions, radii, nucle on momentum distributions, natural orbitals, occupation numbers and depleti ons of the Fermi sea, as well as of pair density and momentum distributions are carried out. A comparison of these quantities for both ground and firs t excited monopole states with the available empirical data and with the re sults of other theoretical methods are given and discussed in detail.