Identifying the closeness of eigenstates in quantum many-body systems
Li Hai-bin1, †, Yang Yang1, Wang Pei1, 2, Wang Xiao-guang3
       

Standard deviation versus average level spacing (energy density) for 1D hard-core boson system with (a) t′ = V′ = 0.0 and (b) t′ = V′ = 1.0. Average level spacings are obtained by where and are the two ends of energy spectrum. The size of subspace N is taken to be 506, 1463, 1771, 4389, and 7084.