eSSENCE@LU 7:3 - Development of atomic basis sets for applications in electronic structure theory

Modern quantum chemistry is able to calculate properties of molecules, liquids, and solids from first principles, i.e., without first getting experimental information about the systems. The wave function of the system, which represents a single state through positions of atomic nuclei and distributions of electrons, is calculated as a combination of a set of standard functions, a basis set. For simple problems, such as calculating the optimal geometry of a small molecule, a small and standard basis set is sufficient, but the standard basis sets used routinely are not well suited for many advanced problems. In those cases, increasing the size of the basis set, which ideally should be infinite, can easily mean a dramatic increase of the computational time with very little improvement of the results.

The goal of this project is to optimize basis sets for specific problems in electronic structure calculations, where the standard basis sets either lose accuracy or are unpractically excessive. The development of compact, but still accurate basis sets will impact all computational codes used by the quantum chemical community. The largest effect will, of course, be for the most time-consuming methods, but even approximate calculations will gain from the usage of compact basis sets for large molecular systems.