Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom~Received 10 May 2000; revised manuscript received 31 July 2000!We describe a semiempirical method for constructing pseudopotentials for use in correlated wave-functioncalculations which involves using a combination of calculated and experimental quantities. The pseudopoten-tials are generated from single-valence-electron configurations and satisfy a norm-conservation condition. Corerelaxation and core-polarization effects are taken into account. Detailed results for a typical atom withs and pvalence electrons ~silicon! and a transition metal atom ~titanium! are given. The method works very well forsilicon but is not satisfactory for titanium.I. INTRODUCTION