Magnetic properties of polyacetylene: Exploring electronic correlation effects through first-principles modeling

Polyacetylene, a simple yet fascinating polymer, has been of great interest for its unique electronic properties. However, the role of electronic correlation effects in polyacetylene still has not been explored fully on an ab initio basis. Using density functional theory (DFT) and a range of exchange-correlation functionals -- including GGA, meta-GGA, and hybrid functionals -- we demonstrate that correlation effects can possibly stabilize a magnetic state as a competing order on the $\pi$-conjugated carbon $p$ orbitals. Our study highlights the complexity of physics of polyacetylene and suggests similarities with the physics of the cuprates.