We are very excited and honoured to welcome Prof Kieron Burke to Bristol for his sabbatical visit. Kieron is here as a Benjamin Meaker Visiting Professor, a scheme provided by the Institute for Advanced Studies. The plan is to work together on a range of areas at the interface between DFT and wavefunction methods. Kieron will be giving various talks and seminars during his visit (details to follow) and a short graduate-level course on exact properties of exchange and correlation functionals in DFT.
We have a postdoc vacancy funded through the DOE Computational Chemical Sciences Research program. The project is a collaboration with Tom Miller and Garnet Chan at Caltech, and focuses on combining quantum chemistry methods, quantum embedding, and dynamics to achieve Ab initio molecular dynamics beyond density-functional theory.
Details of the role, and details of how to apply are here, but you can also just email me to discuss the details or ask questions.
We appreciate and value difference, seeking to attract, develop and retain a diverse mix of talented people that will contribute to the overall success of Bristol and help maintain our position as one of the world’s leading universities.
A warm welcome to Simon McKenzie, who is joining the group for a two-month sabbatical from his PhD with Prof Peter Gill at the Australian National University. Simon will be working on integral technology for the Unsöld project.
Congratulations to Tim Wiles, who passed his PhD viva yesterday, and becomes the first TMCS student to graduate from my group! Tim worked on the Unsöld correlation functional, which we’re now finding allows the construction of accurate DFT approximations with extraordinarily low self-interaction errors. More on that in an up-coming publication…
Congratulations also to former group member Mainak Sadhukhan, who just started a faculty position at the Indian Institute of Technology, Kanpur. Mainak worked in the group as a Royal Society Newton International Fellow, before moving on to work with Alexandre Tkatchenko in Luxembourg.
We’re delighted to welcome Susannah Bourne-Worster and Zack Williams to the group!
Susannah just completed her DPhil with Prof Peter Hore at the University of Oxford, and was awarded a prestigious three-year fellowship by the Royal Commission for the Exhibition of 1851. She will be working on our project on understanding efficiency of energy transport in photosynthesis.
Zack completed year-one of the TMCS programme and has joined the group for his doctoral research. He will be picking up Tim’s project on correlation functionals using the Unsöld approximation.
There are about four or five distinct ingredients used in modern density functionals:
- integrals of functions of the density and its gradients (GGAs, etc)
- inclusion of the kinetic energy density in such expressions (meta-GGAs)
- a fraction of exact Hartree–Fock exchange (or a length-scale-screened variant)
- a contribution from a wavefunction-based correlation method like MP2 or RPA
Now there is another:
Tim Wiles and F R Manby, ‘Wavefunction-like Correlation Model for Use in Hybrid Density Functionals’, J. Chem. Theory Comput., Article ASAP, DOI: 10.1021/acs.jctc.8b00337.
In this paper we introduce the UW12 correlation functional:
- an explicit functional of occupied orbitals (i.e. a functional of the 1-RDM)
- an F12-like model of dynamic electron correlation
- can be self-consistently optimized in a straightforward way
- most of the complicated stuff handled through familiar DFT quadrature
- no double-summation over virtual orbitals, so fast basis-set convergence
This functional can be used as a viable (and hybrid) alternative to use of MP2 in double-hybrid functionals, as we demonstrate in this paper. Our hybrid XCH-BLYP-UW12 functional has only one parameter, and is competitive with more highly parameterised double hybrids for reaction barrier test sets.
If you don’t have access and want to read the paper, just email Fred.
Congratulations to Tim for publishing this work!