Extremal Matching Energy of Bicyclic Graphs

The energy of a graph G is equal to the sum of the absolute values of the eigenvalues of G. Recently, Gutman and Wagner proposed the concept of the matching energy (ME) and pointed out that the chemical applications of ME go back to the 1970s. Let G be a simple graph of order n and 1; 2;:::; n be the roots of its matching polynomial. The matching energy is dened as the sum ∑ n=0 | i|. In this paper, we characterize the graphs with the extremal matching energy among all bicyclic graphs, and completely determine the graphs with the minimal and maximal matching energy in bicyclic graphs.