Exact solution (within a triple-zeta, double polarization basis set) of the electronic Schrödinger equation for water

Using a newly developed density matrix renormalization group algorithm, we have computed exact solutions of the Schrödinger equation for water at two geometries in a basis of 41 orbitals. Calculations of this size cannot be carried out using any other method. We compare our results with high-order coupled cluster and configuration interaction calculations.