TIP4P

A system of 500 TIP4P-model water molecules (2000 interaction sites) with a density of 1.0 g/cm**3 is built up from scratch (using the definition in the tip4p.system build-section). Velocities are randomly generated assuming a Maxwell-Boltzmann distribution.

The particle mesh Ewald (PME) algorithm is employed by using a 20x20x20 grid and b-spline interpolation of 4'th order. The real space sum energies and forces are linearly interpolated from lookup tables.

The nonbonded interactions and real space terms are truncated at a cutoff of 8.0 A. The Verlet-neighborlist cutoff is set to 9.0 A. Neighborlist updating is done every 15'th step.

The forces on the massless virtual sites are redistributed to oxygen and hydrogen sites in the model.

The system is simulated for 100 steps with a timestep of 1.0 fs. The velocities are rescaled every step to fix the temperature at a value of exactly 300.0 K.

Distance constraints are solved by using the SHAKE algorithm. A tolerance of 10**-3 is allowed.