Conventional and unconventional techniques in quantum chemistry

Abstract

The computational cost of ab initio molecular electronic structure calculations is dominated by the generation of electron-electron repulsion integrals, of which there are O(N4), where N is the dimension of the basis set. Even if allowance is made for integral economization schemes, the rapidity with which the computational cost grows as N increases is a problem for all ab initio calculations, particularly the intrinsically more laborious relativistic approaches. There is therefore a strong motive to search for accurate but inexpensive algorithms without having to simplify the equations. We report a preliminary assessment of a promising new scheme that scales much more slowly with N. The key..