Present and future trends in quantum chemical calculations

The state-of-the-art of quantum chemical ab-initio calculations is briefly reviewed with the stress on aspects of traditional methods that are well-established but not yet sufficiently taken care of in routine applications, e.g. gradient methods or the calculation of properties. The suggestion is made that theoretical papers should contain extrapolated “recommended values” in addition to those actually calculated, with some critical discussion of the reliability of the extrapolation used. In the second part methods and ideas are discussed which are not yet ready for routine applications, but which may play an important role in the near future. One aspect is the attempt to construct wave functions which satisfy the nuclear and electronic cusp conditions and which allow a much faster convergence to the exact results than do conventional expansions. Other aspects concern effective Hamiltonians and relativistic theory.