Accurate Energies of Electrons on Spheres
DIPC Seminars
 Speaker

Peter M. W. Gill, Australian National University, Canberra
 When

2018/09/10
14:00  Place
 Donostia International Physics Center
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Density functional theory (DFT) has become the most popular approach within
quantum chemistry but even the most sophisticated functionals suffer from
certain welldocumented weaknesses [1]. In a systematic attempt to improve
this situation, we have been led to reinvestigate the fundamental model on
which DFT is based, namely, the uniform electron gas (UEG).
Several years ago, we showed [2] that traditional DFT functionals which were
designed to be exact for an infinite uniform electron gas (IUEG) are, in fact,
incorrect when applied to a finite uniform electron gas (FUEG) created by
placing n electrons on a sphere [3]. This led us to seek generalizations of
the traditional functionals which are exact, by construction, for both
infinite and finite UEGs [4].
Long ago, Ceperley and Alder performed landmark Quantum Monte Carlo studies
[5] on the correlation energies of IUEGs and their results underpinned the
construction of the widelyused VoskoWilkNusair (VWN) functional [6]. We
now need to perform analogous numerical studies on the correlation energies of
FUEGs and, subsequently, use those results to construct generalizations of
VWN.
In this lecture, I will review our progress in calculating accurate
correlation energies of n samespin electrons on spheres of various radii. In
particular, I will highlight the usefulness of combining careful basis set
extrapolation with Configuration Interaction (CI) calculations using
Configuration State Functions to obtain results which are several orders of
magnitude more accurate than those of Ceperley and Alder.
[1] A. J. Cohen, P. MoriSanchez and W. Yang, Science, **321** , 792 (2008).
[2] P. M. W. Gill and P. F. Loos, Theor. Chem. Acc., **131** , 1069 (2012).
[3] P. F. Loos and P. M. W. Gill, J. Chem. Phys. **135** , 214111 (2011).
[4] P. F. Loos, C. J. Ball and P. M. W. Gill, J. Chem. Phys. **140** , 18A524
(2014).
[5] D. M. Ceperley and B. J. Alder, Phys. Rev. Lett. **45** , 566 (1980).
[6] S. H. Vosko and L. Wilk and M. Nusair, Can. J. Phys. **58** , 1200 (1980).
Host: Eduard Matito