Chemical Fragmentation Approach to the Quantum Chemical Description of Extended Systems

Abstract

The proper description of the electronic structure of extended systems by state-of-the-art methods remains a challenging task [1] of quantum chemistry. In the past few years the notion of “large molecular systems” has undergone a considerable evolution, and species, which seemed almost impossible to treat by ab initio quantum chemistry are now in the domain of routine calculations. This development is mainly due to the revolution of computer technology (vector and/or parallel supercomputers) and new computational techniques, which are better adapted to the new generation of computers, like the direct SCF method [2]. The application of advanced computational techniques made it possible to undertake such spectacular calculations like the ab initio study of the C ₆₀ Buckminsterfullerene [3] or the largest system ever studied by ab initio SCF calculations, the C₁₅₀H₃₀ molecule [4]. It seems that in the very near future several theoretical chemistry laboratories will be in the position to perform routinely calculations on molecules or molecular aggregates, containing 500/600 electrons [5, 6].