Self-consistent mixing methods

The potential mixing method that obtains a new input potential for the next self-consistent step is chosen by

mix_method             broyden, pulay_kerker, or pulay_tf
Default = pulay_kerker

If broyden, the following additional parameter is used.

mixing_energy_cutoff      Sets the broyden mixing energy cutoff.
Default = 5 Ryd

If pulay_tf, the following additional parameters are used

PTF_num_init_PK      gives the number of pulay_kerker mixing
                     steps before the pulay_tf mixing is used.
Default = 2          best performance for Al 20 layer surface

PTF_max_iter_cg      gives the number of conjugate gradient
                     iterations for solving the TFW equations
default = 40

The Broyden method should probably never be used unless someone has a sentimental attachment. For any size relatively homogeneous system, pulay_kerker should be used. For large inhomogeneous systems, pulay_tf should be used; especially for systems with a regions of vacuum such as sufaces, nanotubes, and molecules. Additional information can be obtained at
http://www.nersc.gov/projects/paratec/analysis.htm http://www.nersc.gov/projects/paratec/analysis.htm.