Dear Mr Troyer,
Thank you for your answer.
It needs memory for the sparse Hamiltonian matrix and a few vectors. In your specific example the Hilbert space size is 25 million elements. WHat is your model? a chain? or another lattice?
I know how to write it in the term of graph, i.e. without any translation symmetries. The elementary cell consists of two sites, but there are hopping elements to first-, second- and third-nearest neighbours. Moreover, in order to calculate thermodynamical quantities, I need to have degeneracy of energy level as well as its value, which is impossible in sparcediag.
Thank you for help!
Sincerely yours, Volodymyr Derzhko