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Solvents

For methods that simulate the solvent exactly using classical trajectories, we have a generic infrastructure developed that can be automatically leveraged.

API

A generic solvent is encoded in the Solvents submodule:

The Solvents submodule defines a general Solvent type and an associated PhaseSpace type.

QuantumDynamics.Solvents.Solvent — Type

Abstract type for every solvent. Every solvent needs to implement Base.iterate, which returns the next sample of the phase-space, and a propagate_trajectory method which propagates a given phasespace point using classical mechanics.

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Every solvent allows a phase-space point to be propagated under the internal forces that are present within the solvent and some external force (presumably coming from the system state) using

QuantumDynamics.Solvents.propagate_forced_bath — Function
propagate_forced_bath(bath::HarmonicBath, bps::HarmonicPhaseSpace,
                      f::Vector{Vector{Float64}}, dt::Real, ntimes::Integer)

Propagate the bath subject to constant force f from the system.

This assumes the Hamiltonian of the oscillator is of the form $H = \frac{p^2}{2} + \frac{\omega^2 q^2}{2} - f q.$

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propagate_forced_bath(bath::Solvent, state::PhaseSpace,
                      f::Vector{Vector{Float64}}, dt::Real,
                      ntimes::Integer)

Propagate bath subject to constant force f from the system.

The Hamiltonian for a single bath is assumed to be of the form $H = \sum_i \frac{p_i^2}{2} + V(\{q_i\}) - f_i q_i$ where V(\{q_i\}) is the state-independent potential of the bath.

The time step of the propagation is given by dt, and the number of Verlet steps by ntimes.

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The internal forces of the solvent itself can be calculated using