Energy of Nonsingular Graphs: Improving Lower Bounds

Let be a simple graph of order and be its adjacency matrix. Let be eigenvalues of matrix . Then, the energy of a graph is defined as . In this paper, we will discuss the new lower bounds for the energy of nonsingular graphs in terms of degree sequence, 2-sequence, the first Zagreb index, and chromatic number. Moreover, we improve some previous well-known bounds for connected nonsingular graphs.