High-order geometric derivatives with multilevel coupled cluster theory

Spectroscopy involving molecular vibrations is an important class of experimental techniques, and accurate simulation tools based on computational quantum chemistry can greatly enhance our understanding and interpretation of the observed phenomena in these experiments.

The most accurate quantum chemical methods are, however, very computationally expensive when applied to a full molecular system.

Multilevel methods represent a promising approach for applying such accurate quantum chemical theory to calculate molecular properties for larger systems at a significantly reduced cost by concentrating the high-accuracy description to a limited part of the molecule.

The goal of HOOD is to develop an efficient computational tool with multilevel capability for properties associated with molecular vibrations with coupled cluster as the underlying quantum chemical method.

A novel tool will be applied for the derivation of so-called geometric derivatives which are fundamental in the evaluation of these vibrational properties.

State-of-the-art software will provide the performance-optimized basic multilevel coupled cluster functionality upon which the HOOD feature can be built.

Thanks to these tools, the complexity of the derivation and implementation processes – which constitute the core of this proposal – is significantly reduced, putting the goal within reach.

The successful completion of HOOD will provide the scientific community with a state-of-the-art tool, uniquely facilitating high-accuracy studies of advanced vibrational spectroscopies and significantly expanding the range of systems for which these kind of studies can be undertaken.