What happens to molecules at absolute zero?
molecules cease to exist.
at absolute zero it is believed that the kinetic energy of the electrons goes to zero. This means that the electron density that holds molecules together will not exist. If the electrons have no (or effectively zero) kinetic energy the movement of the electrons that creates the electron density will not exist. This means that there is nothing to hold the molecule together and the molecules will turn to a subatomic "dust".
String theory postulates that all matter is basically vibrations. At absolute zero there would be no motion, kinetic energy or vibrations. Which means matter itself as well as molecules would cease to exist.