Large-Scale Semidefinite Programming for Many-Electron Quantum Mechanics

The energy of a many-electron quantum system can be approximated by a constrained optimization of the two-electron reduced density matrix (2-RDM) that is solvable in polynomial time by semidefinite programming (SDP). Here we develop a SDP method for computing strongly correlated 2-RDMs that is 10-20 times faster than previous methods [D. A. Mazziotti, Phys. Rev. Lett. 93, 213001 (2004)]. We illustrate with (i) the dissociation of N-2 and (ii) the metal-to-insulator transition of H-50. For H-50 the SDP problem has 9.4 x 10(6) variables. This advance also expands the feasibility of large-scale applications in quantum information, control, statistics, and economics.