Multi-Particle Collision Dynamics with Anderson Thermostat

2 Multi-Particle Collision Dynamics with Anderson Thermostat 

Just as SRD, this algorithm conserves momentum at the cell level but not angnlar momentnm. Angnlar momentnm conservation can be restored [32,39] by imposing constraints on the new relative velocities. This leads to an angnlar-momentum conserving modification of MPC-AT [32,38], denoted MPC-AT+a. The collision rule in this case is 

Because d Gaussian random numbers per particle are required at every iteration, where d is the spatial dimension, the speed of the random number generator is the limiting factor for MPC-AT. In contrast, the efficiency of SRD is rather insensitive to the speed of the random number generator since only d — uniformly distributed random nnmbers are needed in every box per iteration, and even a low quality random nnmber generator is sufficient, because the dynamics is self-averaging. A comparison for two-dimensional systems shows that MPC-AT—a is about a factor 2-3 times slower than SRD, and that MPC-AT-l-u is about a factor 1.3-1.5 slower than MPC-AT-fl [40]. 

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