A practical solution to the problem of spurious states in shell-model calculations

An exact numerical method for the removal of spuriousity due to centre-of-mass motion has been proposed using the Lanczos iteration scheme. This method is restricted to configuration spaces defined in a harmonic oscillator basis, which allows an exact factorisation of the centre-of-mass motion. It has been applied to study both the states of negative and positive parity in 16O. The results due to the present method are compared to those obtained in the so-called 'energy-shift method'. (author)