Avogadro; Open source advanced molecular editor designed for cross-platform use in computational chemistry, molecular modeling, bioinformatics, ...; https://es.wikipedia.org/wiki/Avogadro_(software)
VMD; VMD is a molecular visualization program for displaying, animating, and analyzing large biomolecular systems using 3-D graphics and built-in scripting; www.ks.uiuc.edu/Research/vmd/