Andersen Thermostat

Overview

Implements the Andersen thermostat for maintaining a set point temperature through stochastic collisions with a heat bath at some set point temperature T with a specified frequency \(\nu\).

Constructors

FixNVTAndersen(state,handle,groupHandle,temp,nu,applyEvery)
FixNVTAndersen(state,handle,groupHandle,tempFunc,nu,applyEvery)
FixNVTAndersen(state,handle,groupHandle,intervals,temps,nu,applyEvery)

Arguments

state The simulation State to which this fix is to be applied.

handle A name for this fix. String type.

groupHandle The group of atoms to which the fix is applied. String type.

temp The temperature of the heat bath (the set point temperature). Double type.

nu A parameter describing the collision frequency of the system with the heat bath. Float type.

applyEvery The number of turns to elapse between applications of this fix. Integer type.

tempFunc The temperature of the heat bath, as a python function. Python function.

intervals

A list of fractions through the current run for the corresponding list of temperature set points. List of floats.

temps The list of temperature set points for the simulation. List of floats.

Python Member Functions

The Andersen Thermostat allows for user-specification of the seed for the PRNG used to randomly sample from the heat bath. If not specified, the seed takes a default value of 0.

Setting the seed for the PRNG is done with setParameters:

setParameters(seed)

Arguments

seed The seed to be used by the PRNG. Integer value.

Examples

# set up a simulation state to which we will apply the fix
state = State()

# create an instance of the fix
fixNVT = FixNVTAndersen(state,"nvt","all",250.0,0.5,5)

# activate the fix
state.activateFix(fixNVT)