  Quantum dimer model is a low-energy and efficient model to study quantum spin
systems and strong-correlated physics. As a foreseeing step and without loss of
generality, we study the classical dimers on square lattice by means of Monte
Carlo method. For efficient states updating in dimer model, we introduce a
highly-efficient loop updating algorithm directed by energy criterion called
energy directed loop algorithm and improve the pocket algorithm to compare them
with the traditional directed loop algorithm. By comparisons, our energy
directed loop algorithm increases the convergent speed of Monte Carlo and
shorten the auto-correlated time in classical hard-core dimer model. Both the
improved pocket algorithm and energy path algorithm can be used in varietal
dimer models and succeed in traversing the topological sections rapidly.
