A nonequilibrium method for calculating the shear viscosity is presented. It reverses the cause-and-effect picture customarily used in nonequilibrium molecular dynamics: the effect, the momentum flux or stress, is imposed, whereas the cause, the velocity gradient or shear rate, is obtained from the simulation. Reference: F. Müller-Plathe, Phys. Rev. E 59, 4894, 1999.
.. py:class:: RNEMD(all_info, np_per_swap, nslabs, filename)
The constructor of a RNEMD object to implement a shear field.
:param AllInfo all_info: The system information.
:param np_per_swap: The number of particles selected for velocity swap.
:param nslabs: The number of divided slabs of simulation box.
:filename: The name of file for data output including velocity profile, momentum plus and viscosity.
.. py:function:: setSwapPeriod(unsigned int swap_period)
specifies the period of particle velocity swap.
.. py:function:: setProfVelPeriod(unsigned int profvel_period)
specifies the period of profiling velocity of slabs, the default value is 10.
.. py:function:: setSwapGroup(ParticleSet group)
specifies the group of particles for velocity swap.
.. py:function:: setVelProfile(bool vel_profile)
True or False for profiling velocity of slabs.
.. py:function:: setPeriod(unsigned int period)
specifies the period of data output in which the velocity profile and momentum plus will be averaged.
Example::
rnemd = gala.RNEMD(all_info, 1, 30, 'velocity_profile.data')
rnemd.setSwapPeriod(50)
rnemd.setSwapGroup(group)
rnemd.setVelProfile(True)
rnemd.setPeriod(10000)
app.add(rnemd)