BMIX: Difference between revisions

Revision as of 08:22, 20 October 2023

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

\rho_{\rm mix}\left(G\right)=\rho_{\rm in}\left(G\right)+A \frac{G^2}{G^2+B^2}\Bigl(\rho_{\rm out}\left(G\right)-\rho_{\rm in}\left(G\right)\Bigr)

with $A$ =AMIX and $B$ =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).

References

↑ G. P. Kerker, Phys. Rev. B 23, 3082 (1981).

[kerker:prb:81-1] G. P. Kerker, Phys. Rev. B 23, 3082 (1981).

[1]

@@ Line 11: / Line 11: @@
 The parameters for the mixing are optimal if the mean eigenvalue &Gamma;<sub>mean</sub>=1, and if the width of the eigenvalue spectrum is minimal. For an initial linear mixing ({{TAG|BMIX}}&asymp;0) an optimal setting for {{TAG|AMIX}} can be found easily by setting {{TAG|AMIX}}<sub>optimal</sub>={{TAG|AMIX}}<sub>current</sub>*&Gamma;<sub>mean</sub>. For the Kerker scheme ({{TAG|IMIX}}=1) either {{TAG|AMIX}} or {{TAG|BMIX}} can be optimized, but we recommend to change only {{TAG|BMIX}} and keep {{TAG|AMIX}} fixed (you must decrease {{TAG|BMIX}} if the mean eigenvalue is larger than one, and increase {{TAG|BMIX}} if the mean eigenvalue &Gamma;<sub>mean</sub><1).
-== Related Tags and Sections ==
+== Related tags and articles ==
 {{TAG|IMIX}},
 {{TAG|INIMIX}},
@@ Line 22: / Line 22: @@
 {{TAG|WC}}
-== Example Calculations using this Tag ==
+{{sc|BMIX|Examples|Examples that use this tag}}
-{{TAG|constraining local magnetic moments}}, {{TAG|Constraining the local magnetic moments}}, {{TAG|Determining the Magnetic Anisotropy}}, {{TAG|Estimation of J magnetic coupling}}, {{TAG|Including the Spin-Orbit Coupling}}, {{TAG|NiO}}, {{TAG|NiO GGA+U}}, {{TAG|NiO HSE06}}, {{TAG|NiO LSDA+U}}
 == References ==
@@ Line 30: / Line 29: @@
 </references>
 ----
-[[The_VASP_Manual|Contents]]
-[[Category:INCAR]][[Category:Mixing]]
+[[Category:INCAR tag]][[Category:Electronic minimization]][[Category:Density mixing]]