“…The spectral-based graph invariants are widely investigated in the literature, such as inertia index [9,12,15,23,39,37,42,52,44,49,56,57,61] of simple graphs, signed graphs, mixed graphs and complex unit gain graphs, nullity [3,7,6,8,10,14,38,41,45,56,57,64] of simple graphs and signed graphs, rank [1,11,46,47,48,54] of simple graphs, signed graphs and complex unit gain graphs, the H-rank [4,5,50] of mixed graphs and skew-rank [20,22,32,33,26,27,40,53,62] of oriented graphs. The spectral parameter "inertia index" can determine the structure of a graph to some extent and has attracted much attention recently.…”