  A simple, efficient, and accurate method is proposed to map multi-dimensional
free energy landscapes. The method combines the temperature-accelerated
molecular dynamics (TAMD) proposed in [Maragliano & Vanden-Eijnden, Chem. Phys.
Lett. 426, 168 (2006)] with a variational reconstruction method using
radial-basis functions for the representation of the free energy. TAMD is used
to rapidly sweep through the important regions of the free energy landscape and
compute the gradient of the free energy locally at points in these regions. The
variational method is then used to reconstruct the free energy globally from
the mean force at these points. The algorithmic aspects of the single-sweep
method are explained in detail, and the method is tested on simple examples,
compared to metadynamics, and finally used to compute the free energy of the
solvated alanine dipeptide in two and four dihedral angles.
