  We study the von Neumann entropy of a model for two-species hard-core bosons
in one dimension. In this model, the same-species bosons satisfy hard-core
conditions, while the different-species bosons are allowed to occupy the same
site with a local interaction U . At half-filling, by Jordan-Wigner
transformation, the model is exactly mapped to a fermionic Hubbard model. The
phase transition from superfluid U = 0 to Mott insulator U > 0 can be explained
by simple one-band theory at half-filling. We measure the von Neumann
entanglement entropy of the ground states for the half-filled case and away
from half-filling to understand quantum phase transitions. To achieve this
goal, we use a time-evolution-block decimation method with infinite-size matrix
product state and also use a density matrix renormalization group with matrix
product operators with large bond dimensions up to 300. We found strong
evidence that the local minimum point of the von Neumann entanglement entropy
is the quantum critical point for finite-bond-dimension matrix product states.
