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# BMIX

**BMIX** = [real]

Default: **BMIX** = 1.0

Description: **BMIX** sets the cutoff wave vector for Kerker mixing scheme^{[1]} (IMIX=1 and/or INIMIX=1).

The mixed density is given by

with =
AMIX and =
**BMIX**

In VASP the eigenvalue spectrum of the charge dielectric matrix is calculated and written to the OUTCAR file at each electronic step. This allows a rather easy optimization of the mixing parameters, if required. Search in the OUTCAR file for

eigenvalues of (default mixing * dielectric matrix)

The parameters for the mixing are optimal if the mean eigenvalue Γ_{mean}=1, and if the width of the eigenvalue spectrum is minimal. For an initial linear mixing (**BMIX**≈0) an optimal setting for AMIX can be found easily by setting AMIX_{optimal}=AMIX_{current}*Γ_{mean}. For the Kerker scheme (IMIX=1) either AMIX or **BMIX** can be optimized, but we recommend to change only **BMIX** and keep AMIX fixed (you must decrease **BMIX** if the mean eigenvalue is larger than one, and increase **BMIX** if the mean eigenvalue Γ_{mean}<1).

## Related Tags and Sections

IMIX, INIMIX, MAXMIX, AMIX, AMIX_MAG, BMIX_MAG, AMIN, MIXPRE, WC