What is it about?

Our research focuses on a promising method in quantum chemistry known as the random phase approximation (RPA). RPA has gained a lot of attention because it captures complex physical phenomena within chemical systems that many other methods miss, which makes it a very powerful tool for scientists. In recent years, there has been a significant push to refine RPA to make it more efficient. Typically, RPA is not a standalone approach; it relies on a preliminary calculation known as a reference calculation. For efficiency, this initial step is mostly done using standard density functionals, which are methods known for their good balance of cost and performance. However, these functionals have a tendency to overly delocalize the electron density, potentially leading to inaccuracies. Our work introduces a methodology we call Corrected Hartree-Fock RPA, or C(HF)-RPA for short. This approach identifies and corrects the errors in the reference calculation caused by the over-delocalization of charge. The beauty of C(HF)-RPA is that it increases the accuracy of our calculations without sacrificing the efficiency that makes RPA so appealing.

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Why is it important?

Quantum chemistry holds a vital role in scientific research and development due to its ability to both validate and extend experimental findings. For example, it allows scientists to compute NMR spectra to confirm experimental results, explore the intricacies of reaction mechanisms, and sift through vast databases of potential drug candidates to identify the most promising options. However, the effectiveness of quantum chemistry hinges on finding the right balance between accuracy and computational efficiency. Accurate calculations that are also time and resource-efficient can significantly expedite scientific discovery and innovation.

Perspectives

In this work, we've taken a pragmatic route to enhance the accuracy of the random phase approximation (RPA) with an easily adoptable methodology. Our aim was to reinforce the significant potential of RPA in quantum chemistry. We aspire for this contribution to spur a wider acceptance and use of both RPA and its corrected form within the research community.

Daniel Graf
University of Cambridge

Read the Original

This page is a summary of: Corrected density functional theory and the random phase approximation: Improved accuracy at little extra cost, The Journal of Chemical Physics, November 2023, American Institute of Physics,
DOI: 10.1063/5.0168569.
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