Generalized Lanczos method for systematic optimization of tensor network states Project supported by the National Natural Science Foundation of China (Grant Nos. 11190024 and 11474331). |
(color online) Ground-state energy E(n) and entanglement entropy S(n) for the Heisenberg spin chain with L = 20. (a) E(n) and S(n) versus n for D = 2. The red dashed line is the exact ground-state energy, Eex = −8.6824733344. The inset shows the difference between the ground state energy obtained with only one MPS, E(0), and Eex, as a function of D. (b) Relative change of ground-state energy, [E(n) − Eex] / [E(0) − Eex]. |