Combined MPI and CUDA parallelization of the CTQMC algorithm. Each GPU is paired with a CPU, which simulates many independent Markov Chains. The paired CPUs advance the logic of a single Markov Chain until it reaches the dominant computational task: the multiplication of many moderately sized matrices in the trace. This task is handed off to the GPU, while the CPU moves on to the next available Markov chain it controls, until handing that Markov.
In this project, the researchers will leverage these advances in order to compute the response functions in an important class of superconducting materials: the nickelates. In particular, they will compute the response functions in superconducting LaNiO2 across a range of temperatures and electron concentrations. These response functions and their structure in this parameter space will be analyzed in order to gain fundamental insight into unconventional superconductivity.
One of the grand challenges in condensed matter physics is to understand materials wherein the correlations between electrons in d or f orbitals produce a rich tapestry of quantum. The response of a material to stimuli and the response functions which describe this provide invaluable insight into the precise mechanisms through which these phenomena arise. Accurate theoretical calculations of the response functions in strongly correlated materials are only now becoming possible thanks to advances in theory and computational power.
Indeed, the structure of these response functions within the phase diagram will provide important insight into the superconducting glue in the nickelates, the fundamental interactions through which unconventional superconductivity arises in general, and the path towards room temperature superconductivity – a long-standing goal of the DOE and the scientific community, as high-temperature superconductivity would enable an incredibly efficient energy grid, new energy technologies, and more. The project will also illustrate the power of theoretical spectroscopy, wherein computational rather than experimental effort is used to probe a material’s response to some stimulus. That is, it will provide unprecedented detail on the orbitals, the electronic structures, and the interactions through which high-temperature superconductivity manifests at a fraction of the cost. Finally, it will involve the continued development of open-source software which facilitates theoretical spectroscopy and material design
