Some results on chemical energy of graphs

The chemical energy of an nn-vertex graph GG is defined as CE(G)={2∑i=1n2λi(G)if  n  is even ,2∑i=1n−12λi(G)+λn+12(G)if  n  is odd . Here λ1(G),λ2(G),…,λn(G)λ1(G),λ2(G),…,λn(G) are the eigenvalues of GG arranged in non-increasing order. We give lower and upper bounds for the chemical energy of graphs, and determine the extremal unicyclic graphs with minimal and maximal chemical energies.