espressopp.integrator.BerendsenThermostat

This is the Berendsen thermostat implementation according to the original paper [Berendsen84]. If Berendsen thermostat is defined (as a property of integrator) then at the each run the system size and the particle coordinates will be scaled by scaling parameter \(\lambda\) according to the formula:

\[\lambda = [1 + \Delta t/\tau_{T} (T_{0}/T - 1)]^{1/2}\]

where \(\Delta t\) - integration timestep, \(\tau_{T}\) - time parameter (coupling parameter), \(T_{0}\) - external temperature and \(T\) - instantaneous temperature.

Example:

>>> berendsenT = espressopp.integrator.BerendsenThermostat(system)
>>> berendsenT.tau = 1.0
>>> berendsenT.temperature = 1.0
>>> integrator.addExtension(berendsenT)

Definition:

In order to define the Berendsen thermostat

>>> berendsenT = espressopp.integrator.BerendsenThermostat(system)

one should have the System defined.

Properties:

• berendsenT.tau

  The property ‘tau’ defines the time parameter \(\tau_{T}\).

• berendsenT.temperature

  The property ‘temperature’ defines the external temperature \(T_{0}\).

Setting the integration property:

>>> integrator.addExtension(berendsenT)

It will define Berendsen thermostat as a property of integrator.

One more example:

>>> berendsen_thermostat = espressopp.integrator.BerendsenThermostat(system)
>>> berendsen_thermostat.tau = 0.1
>>> berendsen_thermostat.temperature = 3.2
>>> integrator.addExtension(berendsen_thermostat)

Canceling the thermostat:

>>> # define thermostat with parameters
>>> berendsen = espressopp.integrator.BerendsenThermostat(system)
>>> berendsen.tau = 2.0
>>> berendsen.temperature = 5.0
>>> integrator.addExtension(berendsen)
>>> ...
>>> # some runs
>>> ...
>>> # disconnect Berendsen thermostat
>>> berendsen.disconnect()

Connecting the thermostat back after the disconnection

>>> berendsen.connect()

espressopp.integrator.BerendsenThermostat(system)

Parameters:system –