8. Connecting time and space scales

Molecular modeling methods represent matter at the spatio-temporal scale of the atom, whose units are typically the bohr (≍ 0.05 nm) and the femtosecond (10 ^–15 s).

An atomistic simulation based on force fields can apprehend, in the current state of computing capabilities, the temporal evolution of a volume element containing of the order of 10 ⁶ atoms over a duration of the order of nanoseconds (≍ 10 ⁶ time steps).

In ab initio calculation, tracking the order of 10 ³ atoms over a few picoseconds (10 ³ time steps) already represents a tour de force.

While statistical physics assures us that...