Using the potential from N-body simulations , we construct the Galactic bar models with the Schwarzschild method .
By varying the pattern speed and the position angle of the bar , we find that the best-fit bar model has pattern speed \Omega _ { p } = 40 { km s ^ { -1 } kpc ^ { -1 } } , and bar angle \theta _ { bar } = 45 ^ { \circ } . N -body simulations show that the best-fit model is stable for more than 1.5 Gyrs .
Combined with the results in Wang et al .
( 2012 ) , we find that the bar angle and/or the pattern speed are not well constrained by BRAVA data in our Schwarzschild models .
The proper motions predicted from our model are slightly larger than those observed in four fields .
In the future , more kinematic data from the ground and space-based observations will enable us to refine our model of the Milky Way bar .