PLUMED: A portable plugin for free-energy calculations with molecular dynamics. - Massimiliano Bonomi; Davide Branduardi; Giovanni Bussi; Carlo Camilloni; Davide Provasi; Paolo Raiteri; Davide Donadio; Fabrizio Marinelli 002; Fabio Pietrucci; Ricardo A. Broglia; Michele Parrinello (Comput. Phys. Commun., 2009)