{{indexmenu_n>999}}
====== CalculateSelfEnergy ======

###
ResponseFunction.CalculateSelfEnergy($G_0$,$G$) calculates 
\begin{equation} 
\Sigma = G_0^{-1} - G^{-1}
\end{equation}
###
===== Input =====
  * $G_0$ : ResponseFunction object
  * $G$ : ResponseFunction object
  * Possible options are:
      * "epsilon" :  minimal distance between two poles to be considered different in energy (default value 2.3E-13)
===== Output =====
  * $\Sigma$ : ResponseFunction object
===== Example =====
###
###
==== Input ====
<code Quanty CalculateSelfEnergy.Quanty>

-- H0, H1, Npsi, TPes, TIPes are defined beforehand
psiList = Eigensystem(H0,StartRestrictions, Npsi)

G0PESIPES_Spectra, G0PESIPES_ResponseFunction = CreateSpectra(H0, {TPes, TIPes}, psiList[1], {{"Emin",-1}, {"Emax",9}, {"NE",1000}, {"Gamma",0.25}})
G0 = G0PESIPES_ResponseFunction[2]  + ResponseFunction.InvertEnergy(G0PESIPES_ResponseFunction[1])

Eigensystem(H0+H1, psiList[1]) -- Use H0 groundstate as Ansatz for Full Hamiltonian groundstate calculation
--For memory efficiency, this way of calling Eigensystem overwrites Ansatz wavefunction with a new one.  

GPESIPES_Spectra, GPESIPES_ResponseFunction = CreateSpectra(H0+H1, {TPes, TIPes}, psiList[1], {{"Emin",-1}, {"Emax",9}, {"NE",1000}, {"Gamma",0.25}})
G = GPESIPES_ResponseFunction[2]  + ResponseFunction.InvertEnergy(GPESIPES_ResponseFunction[1])

Sigma = ResponseFunction.CalculateSelfEnergy(G0,G)

print(ResponseFunction.ToTable(Sigma))
</code>

==== Result ====
<file Quanty_Output>
{ { 0.5 , 6.9374060711003e-16 , 3.0413812651491 } , 
  { 0.085601012694643 , 0.16439898730536 } ,
  name = Self energy ,
  mu = 0 ,
  type = ListOfPoles }
 </file>
===== Table of contents =====
{{indexmenu>.#1|msort}}