  A modification of the Adaptive Biasing Force method is introduced, in which
the free energy is approximated by a sum of tensor products of one-dimensional
functions. This enables to handle a larger number of reaction coordinates than
the classical algorithm. We prove the algorithm is well-defined and prove the
long-time convergence toward a regularized version of the free energy for an
idealized version of the algorithm. Numerical experiments demonstrate that the
method is able to capture correlations between reaction coordinates.
