Thermally-Assisted-Occupation Density Functional Theory
Jeng-Da Chai1*
1Department of Physics, National Taiwan University, Taipei, Taiwan
* presenting author:Jeng-Da Chai,
In this talk, I will briefly describe the formulation of our recently proposed thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] and the density functional approximations to TAO-DFT [J.-D. Chai, J. Chem. Phys. 140, 18A521 (2014)]. In contrast to Kohn-Sham DFT, TAO-DFT is a DFT with fractional orbital occupations given by the Fermi-Dirac distribution (controlled by a fictitious temperature), for the study of large ground-state systems with strong static correlation effects. Relative to TAO-LDA (i.e., the local density approximation to TAO-DFT), TAO-GGAs (i.e., the generalized-gradient approximations to TAO-DFT) are significantly superior for a wide range of applications, such as thermochemistry, kinetics, and reaction energies. For noncovalent interactions, TAO-GGAs with empirical dispersion corrections are shown to yield excellent performance. Due to their computational efficiency for systems with strong static correlation effects, TAO-LDA and TAO-GGAs are applied to study the electronic properties of acenes with different number of linearly fused benzene rings (up to 100), which is very challenging for conventional electronic structure methods. Some interesting results will be presented in this talk.

Keywords: density functional theory, fractional orbital occupations, Fermi-Dirac distribution, strong static correlation effects, computational efficiency