MOLLER-PLESSET CORRELATION ENERGIES IN A LOCALIZED ORBITAL BASIS USING A LAPLACE TRANSFORM TECHNIQUE

In electronic structure calculations requiring the handling of large a mounts of integrals, storage requirements can often be reduced through the use of localized orbitals which gives rise to sparse integral arr ays. However, conventional Moller-Plesset perturbation theory is const rained to canonical orbitals due to the explicit use of orbital energi es in the energy expressions, and it is therefore not straightforward to reduce the storage requirements through such orbital localization. This work shows how the constraint of canonical orbitals can be lifted using a Laplace transform technique, and investigates the reduction i n storage requirement that can result from the localization of orbital s made possible by such an approach.