Density matrix renormalisation group Lagrangians.
We introduce a Lagrangian formulation of the density matrix renormalisation group (DMRG). We present Lagrangians which, when minimised, yield the optimal DMRG wavefunction in a variational sense, both within the general matrix product ansatz and within the canonical form of the matrix product that is constructed within the DMRG sweep algorithm. Some of the results obtained are similar to elementary expressions in Hartree-Fock theory, and we draw attention to such analogies. The Lagrangians introduced here will be useful in developing theories of analytic response and derivatives in the DMRG.
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA. gc238@cornell.edu
Garnet Kin-Lic
GK
Chan
D000465:Algorithms; D004583:Electrons; D008956:Models, Chemical; D011789:Quantum Theory