Properties and Applications of the Eigenvector Corresponding to the Laplacian Spectral Radius of a Graph

We study the properties of the eigenvector corresponding to the Laplacian spectral radius of a graph and show some applications. We obtain some results on the Laplacian spectral radius of a graph by grafting and adding edges. We also determine the structure of the maximal Laplacian spectrum tree among trees with n vertices and k pendant vertices (n, k fixed), and the upper bound of the Laplacian spectral radius of some trees.