DFT calculations of the structures, electronic and spectral properties for FenSm (2 ≤ n + m ≤ 5) clusters Yuqi Chen, Hongyan Wang, Xiumei Li, Tian Zhang and Hui Wang Eur. Phys. J. D, 73 3 (2019) 59 Published online: 21 March 2019 DOI: 10.1140/epjd/e2019-90640-0