Are DFT level calculations the answer to real-world molecular systems?

This contribution is intended to initiate discussion on the performance of density functional theory based calculations for molecular systems, in particular performance in chemical applications. Compared to a decade ago, it is now possible to study molecular species of a size that is becoming relevant for both the academic as well as for the industrial chemist. But how good are the numbers we generate using such, nowadays almost exclusively, DFT calculations? Despite successes, there seem important cases where current functionals reveal serious discrepancies. This will be illustrated and discuss accuracy and reliability. In addition, throughput of calculations is a real bottleneck. What we may need are quantum computational methods providing us with reliable (relative) energies, for systems up to at least a hundred atoms. Such calculations should be possible on a routine basis. We plead for a set of benchmark systems to evaluate newly introduced functionals, and mutually compare performance of existing methods. (C) 2002 Elsevier Science B.V. All rights reserved.