A multiconfiguration time-dependent Hartree approximation based on natural single-particle states

The time-dependent Schrödinger equation is solved with a multiconfiguration form for the state. It is shown that the use of natural single-particle states results in a minimal number of configurations. The equations of motion of the natural single-particle states are derived by differentation with respect to time of the defining equations, which are eigenvalue equations of reduced density matrices. The method is tested on a two-dimensional model of H2 dissociation on a transition metal surface. It is shown that numerically exact solutions can be obtained. Computation times and memory requirements are less than for methods that solve the time-dependent Schrödinger equation directly.