The level splitting formulae of excited states as well as ground state for
a biaxial spin particle are derived from those of eigenvalues of Schrodinge
r equation (with periodic boundary conditions) which is obtained in terms o
f a quantum treatment of spin, i.e., the potential field description of qua
ntum spin systems, developed by Ulyanov and Zaslavskii. The results obtaine
d are compared with those previously derived by complicated pseudoparticle
methods. (C) 2000 Elsevier Science B.V. All rights reserved.