An efficient projection algorithm and its application to the spurious center-of-mass motion problem

Based on the correspondence of projection to an eigenvalue problem via the underlying group structure, we generalize the projection algorithm proposed by Morrison et al. This algorithm is eligible for large-scale computations, because we can avoid the accumulation of errors. As an example, we apply it to the spurious c.m. motion in a multi-$\hbar\omega$ shell-model calculation. In comparison with Lawson's method, the present method is exact and nevertheless does not need longer CPU time. It is pointed out that the exact treatment of the spurious c.m. motion is crucial to some physical quantities.