C72: A novel low energy and direct band gap carbon phase

•A novel low energy and direct band gap carbon phase was discovered.•The new carbon phase contains 72 atoms per unit cell and was proven to be mechanically and dynamically stable.•The new carbon phase has a substantially lower energy -8.932 eV/atom, which is higher than that of diamond only 0.16 eV/atom.•The new carbon phase exhibits a direct semiconductor character with a band gap of 1.52 eV.