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Difference between revisions of "ANTIRES"

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The flag {{TAG|ANTIRES}} determines whether the Tamm-Dancoff approximation
 
The flag {{TAG|ANTIRES}} determines whether the Tamm-Dancoff approximation
 
is used or not. The allowed settings are:
 
is used or not. The allowed settings are:
 
{|
 
| {{TAG|ANTIRES}} = || 0
 
|-
 
| {{TAG|ANTIRES}} = || 1
 
|-
 
| {{TAG|ANTIRES}} = || 2
 
|}
 
  
 
{{DEF|ANTIRES|0|default: Tamm-Dancoff  approximation (TDA)|1|yields exact results at Ω=0 at roughly the same cost  as TDA|2|beyond Tamm-Dancoff, coupling between positive and negative frequencies}}
 
{{DEF|ANTIRES|0|default: Tamm-Dancoff  approximation (TDA)|1|yields exact results at Ω=0 at roughly the same cost  as TDA|2|beyond Tamm-Dancoff, coupling between positive and negative frequencies}}

Revision as of 19:54, 13 January 2017

ANTIRES = 0 | 1 | 2 

The flag ANTIRES determines whether the Tamm-Dancoff approximation is used or not. The allowed settings are:

Default: ANTIRES = 0 default: Tamm-Dancoff approximation (TDA)
= 1 2
= beyond Tamm-Dancoff, coupling between positive and negative frequencies {{{7}}}

\begin{tabular}{ll} {\tt ANTIRES}=0 & default: Tamm-Dancoff approximation (TDA) \\ {\tt ANTIRES}=1 & yields exact results at $\omega=0$ at roughly the same cost as TDA \\ {\tt ANTIRES}=2 & beyond Tamm-Dancoff, coupling between positive and negative frequencies \end{tabular}

\noindent VASP uses the procedures outlines in Ref. \cite{Sander15} to include contributions beyond Tamm-Dancoff. Beyond TDA calculations increase the compute time and memory requirements by typically a factor 2.



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