### Efficient canonical sampling

A Generalized Langevin dynamics can be tuned so that *all* the vibrational
modes in a system of interest behave as if critically damped. This results in a
more efficient sampling of the constant-temperature canonical ensemble.
Interestingly, this tuning can be done in a a-priori fashion, without knowledge
of the details of the system of interest, so that this **optimal-sampling GLE**
achieves near-ideal sampling efficiency without the need of optimizing the thermostat
parameters on the system of choice.

### Quantum thermostat and PI+GLE

The quantum mechanical behavior of light nuclei (such as hydrogen) can have a dramatic effect
on physical properties of condensed phase systems. For instance, one can extrapolate the pH of
isotopically pure waters to the infinite-mass limit, and estimate that a 'classical' water
would have **pH=8.5**.
An appropriate GLE can enforce a phase-space distribution consistent with a quantum harmonic oscillator
without any significant overhead. This allows one to model nuclear quantum effects in a classical
simulation inexpensively. A systematic improvement of the accuracy in strongly anharmonic problems
can be achieved by combining this approach with path integral molecular dynamics
(with a **much lower** number of replicas than for a fully converged PI simulation).

### Selective normal mode excitation

By tuning the properties of the colored noise it is possible to realize a
stochastic dynamics in which only the normal modes within a narrow range of frquencies
are excited, without prior knowledge of the system's phonon spectrum.