Divide and Conquer QM Development Muller, Ward, Goddard Linear Scaling Massive Parallelizability Form H Diagonalize Did Change? Guess No Done Yes O(N 4 ) PS/Jaguar O(N 2 ) O(N 3 ) Difficult to reduce: Krylof space, Conjugate gradient Currently only important if N > 2000
Divide and Conquer Methods Break a big problem into small problems Physically based in quantum chemistry Divide and Conquer H Hamiltonian: Divided into fragments and buffer zones nbf
Divide and Conquer Results Linear Alkanes –14-98 atoms – bfns Linear scaling AND parallel!
Divide, Conquer, and Recombine Buffer zones don’t scale –Metallic Systems –Same problem n times Hierarchically recombine –E-value decomp of off- diagonal sections –Can also approximate.