green_from_H() [5/6]

template<typename T >

void cntr::green_from_H	(	int	tstp,
		herm_matrix_timestep< T > &	G,
		T	mu,
		cntr::function< T > &	eps,
		T	beta,
		T	h,
		bool	fixHam,
		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

tstp	the index of the time step
G	The output: a timestep of the Greens function set to time dependent free propagator
mu	chemical potential
eps	time dependent representation of quadratical hamiltonian
beta	inverse temperature
h	time step interval
fixHam	If True Hamiltonian is known for all times and no extrapolation is needed for the predictor/corrector
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 1348 of file cntr_equilibrium_impl.hpp.

References cntr::herm_matrix_timestep< T >::size1(), cntr::function< T >::size1_, cntr::function< T >::size2_, and cntr::herm_matrix_timestep< T >::tstp().

                                                                                                                                    {
  assert(tstp == G.tstp());
  assert(G.size1()==eps.size2_);
  assert(eps.size1_==eps.size2_);
  assert(SolveOrder <= MAX_SOLVE_ORDER);
  assert(cf_order == 2 || cf_order == 4);

  int size=G.size1();
  if(size==1) green_from_H_dispatch<T,1>(G,mu,eps,beta,h,SolveOrder,cf_order,fixHam);
  else green_from_H_dispatch<T,LARGESIZE>(G,mu,eps,beta,h,SolveOrder,cf_order,fixHam);
}

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