A variational splitting integrator for quantum molecular dynamics Original Research Article

A numerical time integration method for the nonlinear partial differential equations of the multiconfiguration time-dependent Hartree (MCTDH) approach to quantum molecular dynamics is proposed and analyzed. The method is based on a splitting of the quantum Hamiltonian, though not on the level of the MCTDH equations but of the underlying variational principle. The integrator suffers no step size restriction caused by the unbounded separable part of the Hamiltonian, in contrast to direct time discretizations of the MCTDH equations.