Hyperfine structure of the 2 3P state of 3He with and without an external magnetic field

The hyperfine structure of the 2 P-3 state of He-3 with and without an external magnetic field is precisely calculated. All the linear terms, diamagnetic terms and the alpha(2) relativistic correction terms are included in the Zeeman Hamiltonian. The values of the fields for 32 crossings and 5 anticrossings of the magnetic sublevels are theoretically predicted for magnetic field strengths up to 10 000 gauss. The results are compared with experimental data and other theoretical works. All related matrix elements are calculated with high accuracy by the use of double basis set Hylleraas-type variational wavefunctions.