# LangevinIntegrator Class Reference

This is an Integrator which simulates a System using Langevin dynamics. More...

`#include <LangevinIntegrator.h>`

Inheritance diagram for LangevinIntegrator:

List of all members.

## Public Member Functions
| LangevinIntegrator (double temperature, double frictionCoeff, double stepSize)
| Create a LangevinIntegrator.
double | getTemperature () const
| Get the temperature of the heat bath (in Kelvin).
void | setTemperature (double temp)
| Set the temperature of the heat bath (in Kelvin).
double | getFriction () const
| Get the friction coefficient which determines how strongly the system is coupled to the heat bath (in inverse ps).
void | setFriction (double coeff)
| Set the friction coefficient which determines how strongly the system is coupled to the heat bath (in inverse ps).
int | getRandomNumberSeed () const
| Get the random number seed.
void | setRandomNumberSeed (int seed)
| Set the random number seed.
void | step (int steps)
| Advance a simulation through time by taking a series of time steps.
## Protected Member Functions
void | initialize (ContextImpl &context)
| This will be called by the Context when it is created.
void | cleanup ()
| This will be called by the Context when it is destroyed to let the Integrator do any necessary cleanup.
std::vector< std::string > | getKernelNames ()
| Get the names of all Kernels used by this Integrator.
double | computeKineticEnergy ()
| Compute the kinetic energy of the system at the current time.

## Detailed Description

This is an Integrator which simulates a System using Langevin dynamics.

## Constructor & Destructor Documentation

LangevinIntegrator | ( | double | temperature,
|  | double | frictionCoeff,
|  | double | stepSize |
| ) |  |  |

Create a LangevinIntegrator.

Parameters:

  | temperature | the temperature of the heat bath (in Kelvin)
  | frictionCoeff | the friction coefficient which couples the system to the heat bath (in inverse picoseconds)
  | stepSize | the step size with which to integrator the system (in picoseconds)

## Member Function Documentation

void cleanup | ( |  | ) | `[protected, virtual]`

This will be called by the Context when it is destroyed to let the Integrator do any necessary cleanup.

It will also get called again if the application calls reinitialize() on the Context.

Reimplemented from Integrator.

double computeKineticEnergy | ( |  | ) | `[protected, virtual]`

Compute the kinetic energy of the system at the current time.

Implements Integrator.

double getFriction | ( |  | ) | const`[inline]`

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

Returns:
  the friction coefficient, measured in 1/ps

std::vector<std::string> getKernelNames | ( |  | ) | `[protected, virtual]`

Get the names of all Kernels used by this Integrator.

Implements Integrator.

int getRandomNumberSeed | ( |  | ) | const`[inline]`

Get the random number seed.

See setRandomNumberSeed() for details.

double getTemperature | ( |  | ) | const`[inline]`

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

Returns:
  the temperature of the heat bath, measured in Kelvin

void initialize | ( | ContextImpl & | context | ) | `[protected, virtual]`

This will be called by the Context when it is created.

It informs the Integrator of what context it will be integrating, and gives it a chance to do any necessary initialization. It will also get called again if the application calls reinitialize() on the Context.

Implements Integrator.

void setFriction | ( | double | coeff | ) | `[inline]`

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

Parameters:

  | coeff | the friction coefficient, measured in 1/ps

void setRandomNumberSeed | ( | int | seed | ) | `[inline]`

Set the random number seed.

The precise meaning of this parameter is undefined, and is left up to each Platform to interpret in an appropriate way. It is guaranteed that if two simulations are run with different random number seeds, the sequence of random forces will be different. On the other hand, no guarantees are made about the behavior of simulations that use the same seed. In particular, Platforms are permitted to use non-deterministic algorithms which produce different results on successive runs, even if those runs were initialized identically.

void setTemperature | ( | double | temp | ) | `[inline]`

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

Parameters:

  | temp | the temperature of the heat bath, measured in Kelvin

void step | ( | int | steps | ) | `[virtual]`

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

Parameters:

  | steps | the number of time steps to take

Implements Integrator.

The documentation for this class was generated from the following file:

- LangevinIntegrator.h