Thermally-Assisted-Occupation Density Functional Theory and its Application to Strongly-Correlated Novel Nanomaterials

Sonai Seenithurai^1*, Jeng-Da Chai^1,2

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Center for Theoretical Physics and Center for Quantum Science and Engineering, National Taiwan University, Taipei, Taiwan

* Presenter:Sonai Seenithurai, email:seenithurai@gmail.com

Nanomaterials with strong static correlation effects pose an immense challenge for the Kohn-Sham density functional theory (KS-DFT) with an approximate exchange and correlation functionals. To predict the ground state properties of such challenging systems, thermally-assisted-occupation density functional theory (TAO-DFT) has been developed recently. In contrast to KS-DFT, TAO-DFT is formulated with fractional orbital occupations produced by the Fermi-Dirac distribution function (controlled by a (fictitious) reference temperature) where strong static correlation is described by the entropy contribution. Here we use TAO-DFT to study the electronic and hydrogen storage properties of difference systems such as Li-adsorbed acenes, Li-terminated linear carbon chains and Li-terminated linear boron chains. We have shown that these systems have radical character (polyradical and diradical character) with strong static correlation effects. These systems also can be high-capacity hydrogen strage materials (HSMs) for reversible hydrogen uptake and release at ambient or near-ambient conditions.

References:
Jeng-Da Chai, J. Chem. Phys. 136, 154104 (2012)
Jeng-Da Chai, J. Chem. Phys. 140, 18A521 (2014)
S. Seenithurai et al, Int. Journal of Hydrogen Energy 39, 11016 (2014).
Sonai Seenithurai and Jeng-Da Chai, Sci. Rep. 6, 33081 (2016).
Sonai Seenithurai and Jeng-Da Chai, Sci. Rep. 7, 4966 (2017).
Sonai Seenithurai and Jeng-Da Chai, Sci. Rep. 8, 13538 (2018)

Keywords: electronic structure, density functional theory, strongly correlated electrons, nanomaterials, hydrogen storage applications