NESSi  v1.0.2 The NonEquilibrium Systems Simulation Library

## ◆ green_from_H() [4/6]

template<typename T >
 void cntr::green_from_H ( herm_matrix< T > & G, T mu, cntr::function< T > & eps, T beta, T h, int SolveOrder, int cf_order )

Propagator for time-dependent free Hamiltonian

Purpose

Calculate the free propagator G from time dependent quadratic Hamiltonian using high-order commutator-free exponential time-propagation, see https://doi.org/10.1016/j.jcp.2011.04.006 for the description. Currently implemented versions are the second order using one exponential CF2:1 (order=2) and fourth order using two exponentials CF4:2 (order=4), see also article for more details.

Parameters
 G The output Greens function set to time dependent free propagator mu chemical potential eps time dependent representation of quadratical hamiltonian beta inverse temperature h timestep SolveOrder Order of integrator used for extrapolation and interpolation cf_order Order of approximation for commutator-free exponential, currently implemented orders = 2,4

Definition at line 1196 of file cntr_equilibrium_impl.hpp.

1196  {
1197  assert(G.size1()==eps.size2_);
1198  assert(eps.size1_==eps.size2_);
1199  assert(SolveOrder <= MAX_SOLVE_ORDER);
1200  assert(cf_order == 2 || cf_order == 4);
1201
1202  int size=G.size1();
1203  if(size==1) green_from_H_dispatch<T,1>(G,mu,eps,beta,h,SolveOrder,cf_order,true);
1204  else green_from_H_dispatch<T,LARGESIZE>(G,mu,eps,beta,h,SolveOrder,cf_order,true);
1205 }
int size2_
Number of the rows in the Matrix form.
int size1_
Number of the colums in the Matrix form.
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