ILVES: Accurate and efficient bond length and angle constraints in molecular dynamics

Force field-based molecular dynamics simulations are customarily carried out by constraining internal degrees of freedom. The de facto state-of-the-art algorithms for this purpose, SHAKE, LINCS and P-LINCS, converge slowly, impeding high-accuracy calculations and limiting the realism of simulations. Furthermore, LINCS and P-LINCS cannot handle general angular constraints, which restricts increasing the time step. In this paper, we introduce ILVES, a set of parallel algorithms that converge so rapidly that it is now practical to solve bond length and associated angular constraint equations as accurately as the hardware will allow. We have integrated our work into Gromacs and our analysis demonstrates that, in most cases, our software is superior to the state-of-the-art. We anticipate that ILVES will allow for an increase in the time step, thus accelerating contemporary calculations by a factor of at least 2. This will allow the scientific community to increase the range of phenomena that can therefore be simulated.