These authors remarked that the in the stationary laminar shear case the Hoover-(qp) algorithm does not produce the correct flow pattern. As evident from equ. 8.33 the shear force acts on the ``wrong'' component of the momentum - instead of . This does not destroy the relation between and , but it results in an unphysical flow geometry.

Evans and Morris suggested a simple solution. Instead of 8.26 -8.27 they wrote

For simple Couette flow we now have

where in we have added optional Gaussian constraint forces to keep . It is clear that equ. 8.39 has now the right form to produce Couette flow. In addition, these authors demonstrated that their method produces the correct viscosity up to much higher (non-linear regime) shear values than the Doll's tensor method.

Evans' and Morriss' equations of motion cannot be derived from a perturbed Hamiltonian. However, they fulfill the necessary linear response condition 8.12.

The above equations of motion are known as S'LLOD equations, as they make use of the tensor , the transpose of the DOLL'S tensor .

F. J. Vesely / University of Vienna