Electronic properties of carbon chains by TAO-DFT
Sonai Seenithurai1*, Jeng-Da Chai1,2
1Department of Physics, National Taiwan University, Taipei, Taiwan
2Center for Theoretical Sciences and Center for Quantum Science and Engineering, National Taiwan University, Taipei, Taiwan
* Presenter:Sonai Seenithurai, email:seenithurai@gmail.com
Carbon chains are the challenging materials for the conventional electronic structure methods because of the associated radical character. We have calculated the electronic properties of linear/cyclic carbon chains (l-CC[n]/c-CC[n]) of 10 to 100 atoms using thermally-assisted-occupation density functional theory (TAO-DFT). TAO-DFT results show that l-CC[n]/c-CC[n] are ground state singlets. The electronic properties of some chains exhibit interesting patterns exhibiting oscillations between odd-numbered and even-numbered l-CC[n]. The cyclic chains c-CC[4𝑚+2]/c-CC[4m] exhibit local minima and maxima in their electronic properties for certain positive integer ‘m’ value. The polyradical nature of l-CC[n]/c-CC[n] increases as the size of the chains increases. The active orbitals in the ground state is delocalized over the entire length of l-CC[n] and along the circumference of c-CC[n].

Jeng-Da Chai, Density functional theory with fractional orbital occupations, Journal of Chemical Physics, 136, 154104 (2012).
Sonai Seenithurai and Jeng-Da Chai, TAO-DFT investigation of electronic properties of linear and cyclic carbon chains, Scientific Reports, 10, 13133 (2020)

Keywords: electronic properties, carbon chains, density functional theory (DFT), TAO-DFT, radical character