Model calculations for the prediction of the diradical character of physisorbed molecules: p-benzyne/MgO and p-benzyne/SrO

Abstract

The analysis of the diradical state of functional open-shell molecules is important for understanding their physical properties and chemical reactivity. The diradical character is an important factor in the functional...

Issues on DFT+U calculations of organic diradicals

“…The orbital polarisation effects caused by the stacking of diradical molecules are negligible when using sufficient large vacuum regions. 47 Therefore, in this study, a sufficient vacuum region was adapted, and no dipole correction was added. The sampled k-point was only at the G-points because of the calculation of molecules using the supercell.…”

“…In addition, studies were conducted on real molecules such as p-benzyne and bisphenalenyls. 47,48 Even in the real molecules, as in the model molecules, the diradical characters were varied due to the polarisation effect of the surface on the magnetic orbitals. The contribution of resonance structures of the pbenzyne is affected by the surface adsorption, and the variation causes a decrease of diradical character, which mechanism was not observed in the model molecular system.…”

“…The contribution of resonance structures of the pbenzyne is affected by the surface adsorption, and the variation causes a decrease of diradical character, which mechanism was not observed in the model molecular system. 47 Although theoretical investigation using the diradical molecules in real is important, open-shell singlet states of some organic diradicals are not converged when using the pure-DFT methods. 43,48,49 The self-interaction error (SIE) has a large effect in the pure-DFT, 50 and the closed-shell singlet state in which electrons are delocalised is too stabilised in the calculations of organic diradicals by pure-DFT.…”