Run experiment with a different ode solver

[billlyzhaoyh]

https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.ode.html

Use dopri5 instead of the default vode to avoid running ode solver with one thread per worker only due to the non-reentrant nature of the solvers.

Need to conduct an experiment with:

1. one experiment vode vs dopri5
2. multiple experiments vode vs dopri5