Potential Energy Surfaces for the Chemistry of Cold Matter

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The cooling of atoms and molecules to temperatures very close to absolute zero produces a surprising change in their behaviour as they become dominated by the bizarre effects of quantum mechanics. This fundamentally changes how molecules interact with each other, altering chemical reactions and potentially making them precisely controllable via lasers and magnetic fields. In addition to this controlled chemistry, possible applications of molecules at these temperatures include quantum technologies such as portable atomic clocks for use in next-generation GPS and quantum computers that can solve problems way beyond those that confound current supercomputers.Before these promising advances can be developed, we first need to learn how to cool a wide variety of molecules to the required temperatures, generate further knowledge about how atoms and molecules behave in these extreme conditions, and develop more precise ways of controlling them. This is typically approached by designing and carrying out experiments in exquisite detail, but the input of theoretical quantum chemistry calculations is vital to correctly interpret the results. The aim of this project is to develop new theoretical tools that will increase both the accuracy and efficiency of computing how the energy of these cold systems varies as the relative positions of the atoms/molecules are adjusted, and how the different elements may behave under these conditions. This will require the development of new basis sets for the heavy alkali and alkaline earth metals and combining this with a careful consideration of discrete quantum mechanical effects to develop a computational protocol that can be readily applied to a wide variety of cold matter systems. The first application of the techniques developed is proposed to be an investigation of how calcium fluoride, a molecule that is capable of strong long-range interactions, might be produced at ultracold temperatures through a process known as sympathetic cooling.The methods developed in this work will be made available and accessible to all, but will be of particular interest to both theoreticians and experimentalists working in the cold matter field. The results will be communicated in such a way that interested parties will easily be able to incorporate the methods into their existing work-flow, accelerating the analysis of results and allowing for better predictions and interpretations to be made. Ultimately the results of this work will guide experiment in the right direction, increasing the speed at which progress is made and preventing expensive experiments being carried out on systems that are unlikely to yield useful results.