When a molecule is subjected to an external magnetic field, a situation commonplace in spectroscopic measurements and in practical devices, the standard formulation of DFT does not apply. In this case the universal density functional should depend on both charge-density and current-density.
New approximations for the exchange-correlation energy in weak to ultra-strong fields are required. We have shown how extended meta-GGA functionals can provide high accuracy results at relatively low cost in this regime. Functionals including current-dependence are now available at all rungs of Jacob’s ladder.
Orbital-Free Density-Functional Theory
Orbital-free density functional theory offers the potential to be the most efficient quantum mechanical simulation tool available. However, description of the kinetic energy (KE) of the electrons in terms of the electron density has been the pursuit of theoreticians since the 1920s.
Our work explores the properties of the KE functional, using tools based on highly accurate ab initio methods. In addition we have recently developed a very robust optimization approach for all-electron OF-DFT calculations — allowing use to further interrogate, develop and test new KE functionals.