DrudeLangevinIntegrator

class OpenMM::DrudeLangevinIntegrator

This Integrator simulates systems that include Drude particles. It applies two different Langevin thermostats to different parts of the system. The first is applied to ordinary particles (ones that are not part of a Drude particle pair), as well as to the center of mass of each Drude particle pair. A second thermostat, typically with a much lower temperature, is applied to the relative internal displacement of each pair.

This integrator can optionally set an upper limit on how far any Drude particle is ever allowed to get from its parent particle. This can sometimes help to improve stability. The limit is enforced with a hard wall constraint.

This Integrator requires the System to include a DrudeForce, which it uses to identify the Drude particles.

Methods

DrudeLangevinIntegrator	Create a DrudeLangevinIntegrator.
getTemperature	Get the temperature of the main heat bath (in Kelvin).
setTemperature	Set the temperature of the main heat bath (in Kelvin).
getFriction	Get the friction coefficient which determines how strongly the system is coupled to the main heat bath (in inverse ps).
setFriction	Set the friction coefficient which determines how strongly the system is coupled to the main heat bath (in inverse ps).
getDrudeFriction	Get the friction coefficient which determines how strongly the internal coordinates of Drude particles are coupled to the heat bath (in inverse ps).
setDrudeFriction	Set the friction coefficient which determines how strongly the internal coordinates of Drude particles are coupled to the heat bath (in inverse ps).
step	Advance a simulation through time by taking a series of time steps.

DrudeLangevinIntegrator(double temperature, double frictionCoeff, double drudeTemperature, double drudeFrictionCoeff, double stepSize)

Create a DrudeLangevinIntegrator().

Parameters

• temperature – the temperature of the main heat bath (in Kelvin)

• frictionCoeff – the friction coefficient which couples the system to the main heat bath (in inverse picoseconds)

• drudeTemperature – the temperature of the heat bath applied to internal coordinates of Drude particles (in Kelvin)

• drudeFrictionCoeff – the friction coefficient which couples the system to the heat bath applied to internal coordinates of Drude particles (in inverse picoseconds)

• stepSize – the step size with which to integrator the system (in picoseconds)

double getTemperature() const

Get the temperature of the main heat bath (in Kelvin).

Returns

the temperature of the heat bath, measured in Kelvin

void setTemperature(double temp)

Set the temperature of the main heat bath (in Kelvin).

Parameters

• temp – the temperature of the heat bath, measured in Kelvin

double getFriction() const

Get the friction coefficient which determines how strongly the system is coupled to the main heat bath (in inverse ps).

Returns

the friction coefficient, measured in 1/ps

void setFriction(double coeff)

Set the friction coefficient which determines how strongly the system is coupled to the main heat bath (in inverse ps).

Parameters

• coeff – the friction coefficient, measured in 1/ps

double getDrudeFriction() const

Get the friction coefficient which determines how strongly the internal coordinates of Drude particles are coupled to the heat bath (in inverse ps).

Returns

the friction coefficient, measured in 1/ps

void setDrudeFriction(double coeff)

Set the friction coefficient which determines how strongly the internal coordinates of Drude particles are coupled to the heat bath (in inverse ps).

Parameters

• coeff – the friction coefficient, measured in 1/ps

void step(int steps) override

Advance a simulation through time by taking a series of time steps.

Parameters

• steps – the number of time steps to take