We report on the ab initio discovery of a novel putative ground state for quasi two-dimensional TiO2 through a structural search using the minima hopping method with an artificial neural network potential. The structure is based on a honeycomb lattice and is energetically lower than the experimentally reported lepidocrocite sheet by 7~meV/atom, and merely 13~meV/atom higher in energy than the ground state rutile bulk structure. According to our calculations, the hexagonal sheet is stable against mechanical stress, it is chemically inert and can be deposited on various substrates without disrupting the structure. Its properties differ significantly from all known TiO2 bulk phases with a large gap of 5.05~eV that can be tuned through strain engineering.
@article{arxiv.1704.03983,
title = {A two-dimensional hexagonal sheet of TiO$_2$},
author = {Hossein Asnaashari Eivari and S. Alireza Ghasemi and Hossein Tahmasbi and Samare Rostami and Somayeh Faraji and Robabe Rasoulkhani and Stefan Goedecker and Maximilian Amsler},
journal= {arXiv preprint arXiv:1704.03983},
year = {2017}
}