Mixed ramp-gaussian basis sets

Traditionally, quantum chemists have usually approximated molecular orbitals as sums of either gaussians or plane waves.  However, although these functions have some attractive mathematical properties, they are intrinsically incapable of capturing the cusp that any correct orbital must have at any nucleus.  We are therefore developing new basis sets – containing both gaussians and a new type of cusped function which we call “ramps” – which possess the desirable properties of both function families.  These mixed basis sets have the potential to enable quantum chemical calculations which are both faster and more accurate than those that use all-gaussian basis sets.