-- 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))