AMIX: Difference between revisions

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(Created page with '{{TAGDEF|AMIX|[real]}} {{DEF|AMIX|0.8|if {{TAG|ISPIN}}{{=}}1 and one uses US-PPs|0.4|if {{TAG|ISPIN}}{{=}}2 and one uses US-PPs|0.4|if one uses PAW datasets}} Description: {{TAG…')
 
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Description: {{TAG|AMIX}} specifies the linear mixing parameter.
Description: {{TAG|AMIX}} specifies the linear mixing parameter.
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In VASP the eigenvalue spectrum of the charge dielectric matrix is calculated and written to the {{FILE|OUTCAR}} file at each electronic step. This allows a rather easy optimization of the mixing parameters, if required. Search in the {{FILE|OUTCAR}} file for
eigenvalues of (default mixing * dielectric matrix)
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 Sections ==
{{TAG|IMIX}},
{{TAG|IMIX}},

Revision as of 16:46, 9 February 2011

AMIX = [real] 

Default: AMIX = 0.8 if ISPIN=1 and one uses US-PPs
= 0.4 if ISPIN=2 and one uses US-PPs
= 0.4 if one uses PAW datasets

Description: AMIX specifies the linear mixing parameter.


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 Γmean=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 AMIXoptimal=AMIXcurrentmean. 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 Γmean<1).

Related Tags and Sections

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


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