triqs_ctseg::measure_gl

#include <triqs_ctseg.hpp>

class measure_gl

Measure for the Green’s function in Legendre basis

The Legendre coefficients of the Green’s function and the improved estimator
are defined as
\[X(l)=\sqrt{2l+1}\int_0^\beta d\tau\,P_l[x(\tau)]X(\tau)\]
with \(X=G^\sigma_{ab},F^\sigma_{ab}\), \(x(\tau)=2\tau/\beta-1\) and \(P_l(x)\) are the Legendre polynomials, defined in the [-1,1] interval.
These measurements are controlled through the switches and parameter
measure_gl, measure_fl and n_legendre_g.
The Legendre Green’s function may be transformed to the Matsubara basis

through the unitary transformation

\(G_a(i\omega_n) = \sum_{l\geq 0}T_{nl} G_a(l)\)

where

\(T_{nl} = (-1)^ni^{l+1}\sqrt{2l+1}j_l\left(\frac{(2n+1)\pi}{2}\right)\)

with the spherical Bessel functions \(j_l(z)\).

Public members

params const triqs_ctseg::qmc_parameters *  
config const triqs_ctseg::configuration *  
gl block_gf<triqs::gfs::legendre> &  
fl block_gf<triqs::gfs::legendre> &  
fprefactor std::shared_ptr<precompute_fprefactor>  
beta double  
Z double  
n_l int  
Tn triqs::utility::legendre_generator  

Member functions

(constructor)