Detection of Multiconfigurational States of Hydrogen-Passivated Silicene Nanoclusters

Utilizing density functional theory (DFT) and a complete active space self-consistent field (CASSCF) approach,we study the electronic properties of rectangular silicene nano clusters with hydrogen passivated edges denoted by H-SiNCs (n_z,n_a), with n_z and n_a representing the zigzag and armchair directions, respectively. The results show that in the n_z direction, the H-SiNCs prefer to be in a singlet (S = 0) ground state for n_z > n_a. However, a transition from a singlet (S = 0) to a triplet (S = 1) ground state is revealed for n_a > n_z. Through the calculated Raman spectrum, the S = 0 and S = 1 ground states can be observed by the E_2g (G) and A (D) Raman modes. Furthermore, H-SiNC clusters are shown to have HOMO-LUMO (HL) energy gaps, which decrease as a function of n_a and n_z for S = 0 and S = 1 states. The H-SiNC with a S = 1 ground state can be potentially used for silicene-based spintronic devices.