I have been looking at a publication on Dissipative Particle Dynamics (Groot, Rob & Warren, Patrick. (1997). Dissipative particle dynamics: Bridging the gap between atomistic and mesoscopic simulation) and I came across a comment on the modification of the velocity Verlet algorithm, where it appears a parameter $\lambda$ instead of the usual $\frac12$ in the middle update of velocities, like this: \begin{equation} \tilde{\textbf{v}}_i(t+\Delta t) = \textbf{v}_i(t)+\lambda\Delta t\textbf{f}_i(t)\end{equation}So, my question is related to the sense of this, because as I saw, giving $\lambda=0.65$ leads up to a faster convergence in this case, but is this keeping the sense of an integration algorithm? Or is this just a trick to solve faster the integrations? Should this give the correct results and why?
Also I looked at the book Computer Simulations of Liquids, M. P. Allen and D. J. Tildesley and it did not gave an explanation about this.
