NESSi  v1.0.2
The NonEquilibrium Systems Simulation Library

◆ green_from_H() [2/6]

template<typename T >
void cntr::green_from_H ( int  tstp,
herm_matrix_timestep< T > &  G,
mu,
cdmatrix &  eps,
beta,
h 
)

Propagator for time-independent free Hamiltonian

Purpose

Calculate the free propagator G from fixed 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
tstp

given time step

G

The output: a timestep of the Greens function set to time dependent free propagator

mu

chemical potential

eps

time-independent representation of quadratical hamiltonian

beta

inverse temperature

h

timestep

Definition at line 1249 of file cntr_equilibrium_impl.hpp.

References cntr::herm_matrix_timestep< T >::size1(), and cntr::herm_matrix_timestep< T >::tstp().

1249  {
1250  assert(tstp == G.tstp());
1251  assert(G.size1()==eps.rows());
1252  assert(eps.rows()==eps.cols());
1253 
1254  int size=G.size1();
1255  if(size==1) green_from_H_const_dispatch<T,1>(G,mu,eps,beta,h);
1256  else green_from_H_const_dispatch<T,LARGESIZE>(G,mu,eps,beta,h);
1257 }
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