Accurate wave packet propagation for large molecular systems: The multiconfiguration time-dependent Hartree (MCTDH) method with selected configurations

The multiconfiguration time-dependent Hartree (MCTDH) method is a general, accurate algorithm for wave packet propagation calculations. Its efficiency is due to the use of an optimally small time-dependent basis set which evolves with the wave packet. The method however suffers from an exponential scaling of the required effort with system size, though with a much lower base than the exponential scaling of the standard propagation scheme. Here, we present a method to reduce the computational resources required for MCTDH calculations on large systems by selecting and propagating only the most important configurations for the representation of the wave function. At the same time the properties of the MCTDH method, such as convergence against numerically exact solutions, are retained. (C) 2000 American Institute of Physics. [S0021-9606(00)00219-1].