CASTEP > Dialogs in CASTEP > CASTEP Calculation dialog > Electronic tab > CASTEP Electronic Options dialog > SCF tab > CASTEP Density Mixing Options dialog

The CASTEP Density Mixing Options dialog allows you to specify the parameters that control the Density Mixing method of electronic minimization.

Mixing scheme: Specify the method used for mixing the input densities and output densities from the current iteration to obtain the input density for the next iteration in the iterative solution for the SCF. The supported methods are:

- Linear - the input density and the output density are mixed in a simple linear combination.
- Kerker - the input density and output density are mixed using a reduced mixing factor for the long length scale Fourier coefficients of the density.
- Pulay (default) - the output density is mixed with densities from a number of previous iterations, using the RMM-DIIS method, leading to more rapid convergence.
- Broyden - the output density is mixed with densities from a number of previous iterations, using the quasi-Newton relaxation method. The overall convergence is similar to that of Pulay mixing.

The Pulay or Broyden method is recommended. The Linear method is not usually suitable for large systems.

Charge mixing amplitude: Specify the amplitude of the output charge density to mix with the input charge density to obtain input for the next iteration.

Charge mixing cutoff: Specify the length scale used. Charge mixing is reduced for Fourier coefficients at reciprocal lattice vectors less than about this value.

This option is enabled only if the Kerker, Broyden, or Pulay density mixing method is selected.

DIIS history list: Specify the number of previous iterations to be considered in the DIIS for the Pulay or Broyden density mixing method.

This option is enabled only if the Pulay or Broyden density mixing method is selected.

Spin mixing amplitude: Specify the amplitude of the output spin density to mix with the input spin density to obtain input for the next iteration.

This option is enabled only for spin-polarized calculations.

Spin mixing cutoff: Specify the length scale used. Spin mixing is reduced for Fourier coefficients at reciprocal lattice vectors less than about this value.

This option is enabled only for spin-polarized calculations using the Kerker, Broyden, or Pulay density mixing methods.

Help: Displays

Access methods

Menu | Modules | CASTEP | Calculation | Electronic | More... | SCF | More... |

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Self-consistent electronic minimization

Setting electronic options

SCF tab - CASTEP Electronic Options dialog

Accelrys Materials Studio 8.0 Help: Wednesday, December 17, 2014